CN110892720B

CN110892720B - Encoding device, encoding method, decoding device, and decoding method

Info

Publication number: CN110892720B
Application number: CN201880045386.4A
Authority: CN
Inventors: 大川真人; 斋藤秀雄; 远间正真; 西孝启; 安倍清史; 加纳龙一
Original assignee: Panasonic Intellectual Property Corp of America
Current assignee: Panasonic Intellectual Property Corp of America
Priority date: 2017-07-13
Filing date: 2018-07-11
Publication date: 2022-01-28
Anticipated expiration: 2038-07-11
Also published as: CN114173124A; KR102399384B1; KR20200006171A; CN114173124B; CN114173125A; EP3637767A4; EP4373091A2; JPWO2019013235A1; CN114173123B; CN114173121A; CN114173122A; KR102556279B1; TW202231067A; CN110892720A; CA3086574A1; EP3955572A1; JP7299386B2; US20200322605A1; TW202322631A; PL3637767T3

Abstract

An encoding device (100) for encoding a block to be encoded of a picture, the encoding device being provided with a circuit and a memory, wherein the circuit uses the memory, and generates a 1 st transform coefficient by performing a 1 st transform on a residual signal of the block to be encoded using a 1 st transform base, and when the 1 st transform base matches a predetermined transform base, generates a 2 nd transform coefficient by performing a 2 nd transform on the 1 st transform coefficient using a 2 nd transform base, and quantizes the 2 nd transform coefficient, and when the 1 st transform base is different from the predetermined transform base, quantizes the 1 st transform coefficient without performing the 2 nd transform.

Description

Encoding device, encoding method, decoding device, and decoding method

Technical Field

The present invention relates to encoding and decoding of images/videos in units of blocks.

Background

The Video Coding standard specification called HEVC (High-Efficiency Video Coding) is standardized by JCT-VC (Joint Video Team on Video Coding).

Documents of the prior art

Non-patent document

Non-patent document 1: h.265(ISO/IEC 23008-2 HEVC (high Efficiency Video coding))

Disclosure of Invention

Problems to be solved by the invention

In such encoding and decoding techniques, it is required to reduce the processing load while suppressing a decrease in compression efficiency.

Accordingly, the present invention provides an encoding device, a decoding device, an encoding method, or a decoding method that can reduce the processing load while suppressing a decrease in compression efficiency.

Means for solving the problems

An encoding device according to an aspect of the present invention is an encoding device that encodes a block to be encoded of a picture, and includes a circuit that generates a 1 st transform coefficient by performing a 1 st transform on a residual signal of the block to be encoded using a 1 st transform base using the memory, generates a 2 nd transform coefficient by performing a 2 nd transform on the 1 st transform coefficient using a 2 nd transform base when the 1 st transform base matches a predetermined transform base, quantizes the 2 nd transform coefficient, and quantizes the 1 st transform coefficient without performing the 2 nd transform when the 1 st transform base is different from the predetermined transform base.

These inclusive or specific technical means may be realized by a system, a method, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or may be realized by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

Effects of the invention

The present invention can provide an encoding device, a decoding device, an encoding method, or a decoding method that can reduce the processing load while suppressing a reduction in compression efficiency.

Drawings

Fig. 1 is a block diagram showing a functional configuration of an encoding device according to embodiment 1.

Fig. 2 is a diagram showing an example of block division according to embodiment 1.

Fig. 3 is a table showing transformation basis functions corresponding to respective transformation types.

Fig. 4A is a diagram showing an example of the shape of a filter used in the ALF.

Fig. 4B is a diagram showing another example of the shape of the filter used in the ALF.

Fig. 4C is a diagram showing another example of the shape of the filter used in the ALF.

Fig. 5A is a diagram showing 67 intra prediction modes of intra prediction.

Fig. 5B is a flowchart for explaining an outline of the predicted image correction processing performed by the OBMC processing.

Fig. 5C is a conceptual diagram for explaining an outline of the predicted image correction processing performed by the OBMC processing.

Fig. 5D is a diagram illustrating an example of FRUC.

Fig. 6 is a diagram for explaining pattern matching (bidirectional matching) between 2 blocks along the motion trajectory.

Fig. 7 is a diagram for explaining pattern matching (template matching) between the template in the current picture and the block in the reference picture.

Fig. 8 is a diagram for explaining a model assuming constant-velocity linear motion.

Fig. 9A is a diagram for explaining derivation of a motion vector in units of sub-blocks based on motion vectors of a plurality of adjacent blocks.

Fig. 9B is a diagram for explaining an outline of the motion vector derivation process by the merge mode.

Fig. 9C is a conceptual diagram for explaining an outline of DMVR processing.

Fig. 9D is a diagram for explaining an outline of a predicted image generation method using luminance correction processing by LIC processing.

Fig. 10 is a block diagram showing a functional configuration of a decoding device according to embodiment 1.

Fig. 11 is a flowchart showing a conversion and quantization process in the encoding device according to embodiment 2.

Fig. 12 is a flowchart showing inverse quantization and inverse transform processing in the decoding device according to embodiment 2.

Fig. 13 is a flowchart showing a conversion and quantization process in the encoding device according to embodiment 3.

Fig. 14 is a flowchart showing inverse quantization and inverse transform processing in the decoding device according to embodiment 3.

Fig. 15 is a flowchart showing a conversion and quantization process in the encoding device according to embodiment 4.

Fig. 16 is a flowchart showing inverse quantization and inverse transform processing in the decoding apparatus according to embodiment 4.

Fig. 17 is a flowchart showing an encoding process in the encoding device according to embodiment 5.

Fig. 18 is a diagram showing a specific example of syntax according to embodiment 5.

Fig. 19 is a flowchart showing a decoding process in the decoding device according to embodiment 5.

Fig. 20 is a flowchart showing an encoding process in the encoding device according to embodiment 6.

Fig. 21 is a flowchart showing a decoding process in the decoding device according to embodiment 6.

Fig. 22 is an overall configuration diagram of a content providing system that realizes a content distribution service.

Fig. 23 is a diagram showing an example of an encoding structure in hierarchical encoding.

Fig. 24 is a diagram showing an example of an encoding structure in hierarchical encoding.

Fig. 25 is a diagram showing an example of a display screen of a web page.

Fig. 26 is a diagram showing an example of a display screen of a web page.

Fig. 27 is a diagram showing an example of a smartphone.

Fig. 28 is a block diagram showing a configuration example of the smartphone.

Detailed Description

(insight underlying the present disclosure)

In Joint Video Exploration Team (Joint Exploration Test Model) software of jfet (Joint Video Exploration Team), frequency conversion of two stages of a block to which intra prediction is applied is proposed. In the two-stage frequency Transform, EMT (Explicit Multiple Core Transform) is used as a primary Transform, and NSST (Non-separable Secondary Transform) is used as a Secondary Transform. In EMT, a plurality of transform bases are adaptively selected, and transform from a spatial region to a frequency domain is performed.

In such two-stage frequency conversion, there is room for improvement from the viewpoint of throughput.

Hereinafter, embodiments based on such findings will be specifically described with reference to the drawings.

The embodiments described below are all illustrative or specific examples. The numerical values, shapes, materials, constituent elements, arrangement and connection forms of constituent elements, steps, order of steps, and the like shown in the following embodiments are examples and are not intended to limit the scope of the claims. Further, among the components of the following embodiments, components that are not recited in the independent claims representing the uppermost concept will be described as arbitrary components.

(embodiment mode 1)

First, an outline of embodiment 1 will be described as an example of an encoding device and a decoding device to which processing and/or a configuration described in each aspect of the present invention will be applied. However, embodiment 1 is merely an example of an encoding device and a decoding device to which the processing and/or configuration described in each aspect of the present invention can be applied, and the processing and/or configuration described in each aspect of the present invention can be applied to an encoding device and a decoding device different from embodiment 1.

When the processing and/or configuration described in each aspect of the present invention is applied to embodiment 1, any of the following processes may be performed, for example.

(1) The encoding device or the decoding device according to embodiment 1 is configured such that, among a plurality of components constituting the encoding device or the decoding device, a component corresponding to a component described in each aspect of the present invention is replaced with a component described in each aspect of the present invention;

(2) with the encoding device or the decoding device according to embodiment 1, after any change such as addition, replacement, deletion, or the like of functions or processing to be performed is applied to some of the plurality of constituent elements constituting the encoding device or the decoding device, the constituent elements corresponding to the constituent elements described in the respective aspects of the present invention are replaced with the constituent elements described in the respective aspects of the present invention;

(3) in the method implemented by the encoding device or the decoding device according to embodiment 1, after adding a process and/or arbitrarily changing a part of the processes included in the method such as replacement or deletion, a process corresponding to the process described in each aspect of the present invention is replaced with the process described in each aspect of the present invention;

(4) a part of the plurality of components constituting the encoding device or the decoding device according to embodiment 1 is combined with the components described in the respective embodiments of the present invention, the components having a part of the functions of the components described in the respective embodiments of the present invention, or the components performing a part of the processes performed by the components described in the respective embodiments of the present invention;

(5) a combination of a component having a part of functions of a part of a plurality of components constituting the encoding device or the decoding device of embodiment 1 or a component performing a part of processing performed by a part of a plurality of components constituting the encoding device or the decoding device of embodiment 1 with a component described in each aspect of the present invention, a component having a part of functions of a component described in each aspect of the present invention, or a component performing a part of processing performed by a component described in each aspect of the present invention;

(6) with respect to the method implemented by the encoding device or the decoding device of embodiment 1, the processing corresponding to the processing described in each aspect of the present invention among the plurality of processing included in the method is replaced with the processing described in each aspect of the present invention;

(7) some of the plurality of processes included in the method performed by the encoding device or the decoding device according to embodiment 1 are combined with the processes described in the respective aspects of the present invention.

The embodiments of the processing and/or configuration described in the embodiments of the present invention are not limited to the above examples. For example, the present invention may be implemented in a device used for a purpose different from that of the moving image/image encoding device or the moving image/image decoding device disclosed in embodiment 1, or the processes and/or configurations described in the respective embodiments may be implemented separately. Further, the processes and/or structures described in the different embodiments may be combined and implemented.

[ overview of encoding apparatus ]

First, an outline of the coding apparatus according to embodiment 1 will be described. Fig. 1 is a block diagram showing a functional configuration of an encoding device 100 according to embodiment 1. The encoding apparatus 100 is a moving image/image encoding apparatus that encodes moving images/images in units of blocks.

As shown in fig. 1, the encoding device 100 is a device that encodes an image in units of blocks, and includes a dividing unit 102, a subtracting unit 104, a transforming unit 106, a quantizing unit 108, an entropy encoding unit 110, an inverse quantizing unit 112, an inverse transforming unit 114, an adding unit 116, a block memory 118, a loop filtering unit 120, a frame memory 122, an intra-prediction unit 124, an inter-prediction unit 126, and a prediction control unit 128.

The encoding device 100 is implemented by, for example, a general-purpose processor and a memory. In this case, when the software program stored in the memory is executed by the processor, the processor functions as the dividing unit 102, the subtracting unit 104, the transforming unit 106, the quantizing unit 108, the entropy encoding unit 110, the inverse quantizing unit 112, the inverse transforming unit 114, the adding unit 116, the loop filtering unit 120, the intra prediction unit 124, the inter prediction unit 126, and the prediction control unit 128. The encoding device 100 may be implemented as 1 or more dedicated electronic circuits corresponding to the dividing unit 102, the subtracting unit 104, the transforming unit 106, the quantizing unit 108, the entropy encoding unit 110, the inverse quantizing unit 112, the inverse transforming unit 114, the adding unit 116, the loop filtering unit 120, the intra-prediction unit 124, the inter-prediction unit 126, and the prediction control unit 128.

Hereinafter, each component included in the encoding device 100 will be described.

[ division part ]

The dividing unit 102 divides each picture included in the input moving image into a plurality of blocks, and outputs each block to the subtracting unit 104. For example, the divider 102 first divides a picture into blocks of a fixed size (e.g., 128 × 128). This fixed size block is sometimes referred to as a Code Tree Unit (CTU). The dividing unit 102 divides each block of a fixed size into blocks of variable sizes (for example, 64 × 64 or less) based on recursive quadtree (quadtree) and/or binary tree (binary tree) block division. This variable-size block may be referred to as a Coding Unit (CU), a Prediction Unit (PU), or a Transform Unit (TU). In the present embodiment, it is not necessary to distinguish the CU, PU, and TU, and a part or all of the blocks in the picture may be used as the processing unit of the CU, PU, and TU.

Fig. 2 is a diagram showing an example of block division according to embodiment 1. In fig. 2, a solid line indicates a block boundary based on the quad-tree block division, and a dotted line indicates a block boundary based on the binary-tree block division.

Here, the block 10 is a square block of 128 × 128 pixels (128 × 128 block). The 128 × 128 block 10 is first divided into 4 square 64 × 64 blocks (quad-tree block division).

The upper left 64 × 64 block is then vertically divided into 2 rectangular 32 × 64 blocks, and the left 32 × 64 block is then vertically divided into 2 rectangular 16 × 64 blocks (binary tree block division). As a result, the upper left 64 × 64 block is divided into 216 × 64

blocks

11, 12, and 32 × 64 block 13.

The upper right 64 × 64 block is horizontally divided into 2 rectangular 64 × 32 blocks 14, 15 (binary tree block division).

The lower left 64 × 64 block is divided into 4 square 32 × 32 blocks (quad-tree block division). The upper left block and the lower right block of the 4 32 × 32 blocks are further divided. The upper left 32 × 32 block is vertically divided into 2 rectangular 16 × 32 blocks, and the right 16 × 32 block is horizontally divided into 216 × 16 blocks (binary tree block division). The lower right 32 × 32 block is horizontally divided into 2 32 × 16 blocks (binary tree block division). As a result, the lower left 64 block is divided into 16 × 32

blocks

16, 216 × 16

blocks

17, 18, 2 32 × 32

blocks

19, 20, and 2 32 × 16

blocks

21, 22.

The lower right 64 x 64 block 23 is not partitioned.

As described above, in fig. 2, the block 10 is divided into 13 variable-size blocks 11 to 23 by recursive quadtree and binary tree block division. Such a partition is sometimes called a QTBT (quad-tree plus binary tree) partition.

In fig. 2, 1 block is divided into 4 or 2 blocks (quad tree or binary tree block division), but the division is not limited thereto. For example, 1 block may be divided into 3 blocks (ternary tree division). A partition including such a ternary tree partition is sometimes called an MBT (multi type tree) partition.

[ subtracting section ]

The subtracting unit 104 subtracts the prediction signal (prediction sample) from the original signal (original sample) in block units divided by the dividing unit 102. That is, the subtraction unit 104 calculates a prediction error (also referred to as a residual) of a block to be encoded (hereinafter, referred to as a current block). The subtraction unit 104 then outputs the calculated prediction error to the conversion unit 106.

The original signal is an input signal to the encoding apparatus 100, and is a signal (for example, a luminance (luma) signal and 2 color difference (chroma) signals) representing an image of each picture constituting a moving image. Hereinafter, a signal representing an image may be also referred to as a sample.

[ converting part ]

The transform unit 106 transforms the prediction error in the spatial domain into a transform coefficient in the frequency domain, and outputs the transform coefficient to the quantization unit 108. Specifically, the transform unit 106 performs, for example, Discrete Cosine Transform (DCT) or Discrete Sine Transform (DST) set in advance on the prediction error in the spatial domain.

The transform unit 106 may adaptively select a transform type from among a plurality of transform types, and transform the prediction error into a transform coefficient using a transform basis function (transform basis function) corresponding to the selected transform type. Such a transform may be called an EMT (explicit multiple core transform) or an AMT (adaptive multiple transform).

The plurality of transform types includes, for example, DCT-II, DCT-V, DCT-VIII, DST-I, and DST-VII. Fig. 3 is a table showing transformation basis functions corresponding to respective transformation types. In fig. 3, N denotes the number of input pixels. The selection of a transform type from among these multiple transform types may depend on, for example, the type of prediction (intra prediction and inter prediction) or the intra prediction mode.

Information indicating whether such EMT or AMT is applied (e.g., referred to as AMT flag) and information indicating the selected transform type are signaled at CU level. The signaling of the information is not necessarily limited to the CU level, and may be at another level (for example, a sequence level, a picture level, a slice level, a tile level, or a CTU level).

The transform unit 106 may perform a retransformation of the transform coefficient (transform result). Such a retransformation may be referred to as AST (adaptive secondary transform) or NSST (non-secondary transform). For example, the transform unit 106 performs re-transform on each sub-block (for example, 4 × 4 sub-blocks) included in a block of transform coefficients corresponding to an intra prediction error. Information indicating whether NSST is applied and information on a transform matrix used in NSST are signaled at the CU level. The signaling of the information is not necessarily limited to the CU level, and may be at another level (for example, a sequence level, a picture level, a slice level, a tile level, or a CTU level).

Here, Separable conversion refers to a system of performing conversion a plurality of times by separating in each direction as much as the number of dimensions of the input, and Non-Separable conversion refers to a system of performing conversion collectively by regarding 2 or more dimensions as 1 dimension when the input is multidimensional.

For example, as 1 example of the Non-Separable transform, a method may be mentioned in which when a 4 × 4 block is input, the block is regarded as one permutation having 16 elements, and the permutation is subjected to transform processing using a 16 × 16 transform matrix.

Similarly, a scheme (Hypercube Givens Transform) in which a 4 × 4 input block is regarded as one permutation having 16 elements and then Givens rotation is performed on the permutation a plurality of times is also an example of Non-Separable conversion.

[ quantifying section ]

The quantization unit 108 quantizes the transform coefficient output from the transform unit 106. Specifically, the quantization unit 108 scans the transform coefficient of the current block in a predetermined scanning order and quantizes the transform coefficient based on a Quantization Parameter (QP) corresponding to the scanned transform coefficient. The quantization unit 108 outputs the quantized transform coefficient (hereinafter, referred to as a quantization coefficient) of the current block to the entropy coding unit 110 and the inverse quantization unit 112.

The prescribed order is an order for quantization/inverse quantization of the transform coefficients. For example, the predetermined scanning order is defined in ascending order (order from low frequency to high frequency) or descending order (order from high frequency to low frequency) of the frequency.

The quantization parameter refers to a parameter that defines a quantization step (quantization width). For example, if the value of the quantization parameter increases, the quantization step size also increases. That is, if the value of the quantization parameter increases, the quantization error increases.

[ entropy encoding part ]

The entropy encoding unit 110 generates an encoded signal (encoded bit stream) by variable-length encoding the quantized coefficients input from the quantization unit 108. Specifically, the entropy encoding unit 110 binarizes the quantized coefficient, for example, and arithmetically encodes the binary signal.

[ inverse quantization part ]

The inverse quantization unit 112 inversely quantizes the quantization coefficient which is input from the quantization unit 108. Specifically, the inverse quantization unit 112 inversely quantizes the quantized coefficients of the current block in a predetermined scanning order. Then, the inverse quantization unit 112 outputs the inverse-quantized transform coefficient of the current block to the inverse transform unit 114.

[ inverse transformation section ]

The inverse transform unit 114 performs inverse transform on the transform coefficient input from the inverse quantization unit 112 to restore the prediction error. Specifically, the inverse transform unit 114 performs inverse transform corresponding to the transform performed by the transform unit 106 on the transform coefficient, thereby restoring the prediction error of the current block. The inverse transform unit 114 outputs the restored prediction error to the addition unit 116.

The restored prediction error loses information by quantization, and therefore does not match the prediction error calculated by the subtraction unit 104. That is, the prediction error after restoration includes a quantization error.

[ addition section ]

The addition section 116 reconstructs the current block by adding the prediction error, which is an input from the inverse transform section 114, to the prediction sample, which is an input from the prediction control section 128. The adder 116 outputs the reconstructed block to the block memory 118 and the loop filter 120. There are cases where the reconstructed block is called a native decoding block.

[ Block memory ]

The block memory 118 is a storage unit for storing a block in a picture to be encoded (hereinafter, referred to as a current picture) which is referred to in intra prediction. Specifically, the block memory 118 stores the reconstructed block output from the adder 116.

[ Cyclic Filter Unit ]

The loop filter unit 120 applies loop filtering to the block reconstructed by the adder unit 116, and outputs the filtered reconstructed block to the frame memory 122. The loop filtering refers to filtering (in-loop filtering) used in an encoding loop, and includes, for example, Deblocking Filtering (DF), Sample Adaptive Offset (SAO), Adaptive Loop Filtering (ALF), and the like.

In the ALF, a least square error filter for removing coding distortion is used, and for example, 1 filter selected from a plurality of filters based on the direction and activity (activity) of a local gradient (gradient) is used for each 2 × 2 sub-block in a current block.

Specifically, first, sub-blocks (e.g., 2 × 2 sub-blocks) are classified into a plurality of classes (e.g., 15 or 25 classes). The sub-blocks are classified based on the direction of the gradient and the activity. For example, the classification value C (e.g., C ═ 5D + a) is calculated using the direction value D (e.g., 0 to 2 or 0 to 4) of the gradient and the activity value a (e.g., 0 to 4) of the gradient. And, the sub-blocks are classified into a plurality of classes (e.g., 15 or 25 classes) based on the classification value C.

The direction value D of the gradient is derived, for example, by comparing the gradients in a plurality of directions (e.g., horizontal, vertical, and 2 diagonal directions). The activity value a of the gradient is derived by, for example, adding the gradients in a plurality of directions and quantifying the addition result.

Based on the result of such classification, a filter for a sub-block is decided from among a plurality of filters.

As the shape of the filter used in the ALF, for example, a circularly symmetric shape is used. Fig. 4A to 4C are diagrams showing a plurality of examples of the shape of a filter used in the ALF. Fig. 4A shows a 5 × 5 diamond shaped filter, fig. 4B shows a 7 × 7 diamond shaped filter, and fig. 4C shows a 9 × 9 diamond shaped filter. Information representing the shape of the filter is signaled at the picture level. The signaling of the information indicating the shape of the filter is not necessarily limited to the picture level, and may be at another level (for example, the sequence level, slice level, tile level, CTU level, or CU level).

The turning on/off of the ALF is determined, for example, at the picture level or CU level. For example, regarding luminance, it is decided whether or not ALF is used at CU level, and regarding color difference, it is decided whether or not ALF is used at picture level. Information indicating on/off of the ALF is signaled at a picture level or a CU level. The signaling of the information indicating the turning on/off of the ALF is not necessarily limited to the picture level or the CU level, and may be other levels (for example, the sequence level, the slice level, the tile level, or the CTU level).

The coefficient sets of a selectable plurality of filters (e.g., up to 15 or 25 filters) are signaled at the picture level. The signaling of the coefficient set is not necessarily limited to the picture level, and may be at other levels (for example, a sequence level, a slice level, a tile level, a CTU level, a CU level, or a sub-block level).

[ frame memory ]

The frame memory 122 is a storage unit for storing reference pictures used for inter-frame prediction, and may be referred to as a frame buffer. Specifically, the frame memory 122 stores the reconstructed block filtered by the loop filter unit 120.

[ Intra prediction Unit ]

The intra prediction unit 124 performs intra prediction (also referred to as intra prediction) of the current block with reference to the block in the current picture stored in the block memory 118, thereby generating a prediction signal (intra prediction signal). Specifically, the intra prediction unit 124 performs intra prediction by referring to samples (for example, luminance values and color difference values) of blocks adjacent to the current block to generate an intra prediction signal, and outputs the intra prediction signal to the prediction control unit 128.

For example, the intra prediction unit 124 performs intra prediction using 1 of a plurality of predetermined intra prediction modes. The plurality of intra prediction modes include 1 or more non-directional prediction modes and a plurality of directional prediction modes.

The 1 or more non-directional prediction modes include, for example, a Planar prediction mode and a DC prediction mode defined in the h.265/HEVC (High-Efficiency Video Coding) specification (non-patent document 1).

The plurality of directional prediction modes includes, for example, 33 directional prediction modes specified by the h.265/HEVC specification. The plurality of directional prediction modes may include prediction modes in 32 directions (65 directional prediction modes in total) in addition to 33 directions. Fig. 5A is a diagram showing 67 intra prediction modes (2 non-directional prediction modes and 65 directional prediction modes) in intra prediction. The solid arrows indicate 33 directions defined by the h.265/HEVC specification, and the dashed arrows indicate the additional 32 directions.

In the intra prediction of the color difference block, the luminance block may be referred to. That is, the color difference component of the current block may also be predicted based on the luminance component of the current block. Such intra-frame prediction is sometimes called CCLM (cross-component linear model) prediction. The intra prediction mode (for example, referred to as CCLM mode) of the color difference block of the reference luminance block may be added as 1 intra prediction mode of the color difference block.

The intra prediction unit 124 may correct the pixel value after intra prediction based on the gradient of the reference pixel in the horizontal/vertical direction. The intra prediction associated with such correction is sometimes called PDPC (position dependent intra prediction combination). Information indicating whether PDPC is used or not (for example, referred to as a PDPC flag) is signaled, for example, on the CU level. The signaling of the information is not necessarily limited to the CU level, and may be at another level (for example, a sequence level, a picture level, a slice level, a tile level, or a CTU level).

[ interframe prediction part ]

The inter prediction unit 126 performs inter prediction (also referred to as inter prediction) of the current block with reference to a reference picture different from the current picture stored in the frame memory 122, thereby generating a prediction signal (inter prediction signal). Inter prediction is performed in units of a current block or a subblock (e.g., a 4 × 4 block) within the current block. For example, the inter prediction unit 126 performs motion estimation (motion estimation) on the current block or the sub-block within the reference picture. The inter prediction unit 126 performs motion compensation using motion information (e.g., a motion vector) obtained by motion estimation, and generates an inter prediction signal of the current block or sub-block. The inter prediction unit 126 then outputs the generated inter prediction signal to the prediction control unit 128.

The motion information used in motion compensation is signaled. A predictive motion vector predictor (motion vector predictor) may also be used for the signaling of motion vectors. That is, the difference between the motion vector and the predicted motion vector may be signaled.

In addition, the inter prediction signal may be generated using not only the motion information of the current block obtained through motion estimation but also the motion information of the neighboring blocks. Specifically, the inter prediction signal may be generated in units of sub blocks within the current block by performing weighted addition of a prediction signal based on motion information obtained by motion estimation and a prediction signal based on motion information of an adjacent block. Such inter-frame prediction (motion compensation) is sometimes called OBMC (overlapped block motion compensation).

In such an OBMC mode, information indicating the size of a sub-block used for OBMC (for example, referred to as an OBMC block size) is signaled at a sequence level. Further, information indicating whether the OBMC mode is adopted (for example, referred to as an OBMC flag) is signaled at the CU level. The level of signaling of such information is not necessarily limited to the sequence level and CU level, and may be other levels (for example, picture level, slice level, tile level, CTU level, or sub-block level).

The OBMC mode will be explained more specifically. Fig. 5B and 5C are a flowchart and a conceptual diagram for explaining an outline of the predicted image correction processing performed by the OBMC processing.

First, a prediction image (Pred) obtained by normal motion compensation is acquired using a Motion Vector (MV) assigned to a block to be encoded.

Next, a predicted image (Pred _ L) is obtained for the block to be encoded using the motion vector (MV _ L) of the left adjacent block that has been encoded, and the predicted image and Pred _ L are superimposed by weighting, thereby performing the 1 st correction of the predicted image.

Similarly, a predicted image (Pred _ U) is obtained for the block to be encoded using the motion vector (MV _ U) of the encoded adjacent block, and the predicted image subjected to the 1 st correction and Pred _ U are weighted and superimposed to perform the 2 nd correction of the predicted image, thereby obtaining the final predicted image.

In addition, although the method of performing two-stage correction using the left adjacent block and the upper adjacent block is described here, the correction may be performed more times than two stages using the right adjacent block and the lower adjacent block.

The region to be superimposed may be not the entire pixel region of the block but only a partial region in the vicinity of the block boundary.

In addition, although the predicted image correction processing based on 1 reference picture is described here, the same applies to the case where the predicted image is corrected based on a plurality of reference pictures, and the corrected predicted images are acquired from the respective reference pictures and then the acquired predicted images are further superimposed to form the final predicted image.

The target block may be a prediction block unit, or may be a sub-block unit obtained by dividing a prediction block.

As a method of determining whether or not OBMC processing is employed, for example, a method of using an OBMC _ flag which is a signal indicating whether or not OBMC processing is employed. As a specific example, the encoding apparatus determines whether or not the block to be encoded belongs to a region with a complicated motion, sets a value of 1 as the OBMC _ flag and encodes the block by the OBMC process when the block belongs to the region with a complicated motion, and sets a value of 0 as the OBMC _ flag and encodes the block without the OBMC process when the block does not belong to the region with a complicated motion. On the other hand, the decoding device decodes the OBMC _ flag described in the stream, and switches whether or not to perform OBMC processing according to the value of the OBMC _ flag, thereby performing decoding.

In addition, the motion information may not be converted into a signal, but may be derived by the decoding apparatus. For example, the merge mode specified by the H.265/HEVC specification may also be used. Further, for example, motion information may be derived by performing motion estimation on the decoding apparatus side. In this case, motion estimation is performed without using pixel values of the current block.

Here, a mode in which motion estimation is performed on the decoding apparatus side will be described. The mode for performing motion estimation on the decoding apparatus side is called a PMMVD (pattern matched motion vector derivation) mode or a FRUC (frame rate up-conversion) mode.

Fig. 5D shows an example of FRUC processing. First, a list (which may be shared by a merge list) of a plurality of candidates each having a predicted motion vector is generated with reference to a motion vector of an encoded block spatially or temporally adjacent to the current block. Next, the best candidate MV is selected from among the plurality of candidate MVs registered in the candidate list. For example, the evaluation value of each candidate included in the candidate list is calculated, and 1 candidate is selected based on the evaluation values.

And deriving a motion vector for the current block based on the selected candidate motion vector. Specifically, for example, the motion vector of the selected candidate (best candidate MV) is derived as it is as a motion vector for the current block. Further, for example, the motion vector for the current block may be derived by performing pattern matching in a peripheral region of a position in the reference picture corresponding to the selected candidate motion vector. That is, the neighboring area of the optimal candidate MV may be searched by the same method, and when there is an MV having a better evaluation value, the optimal candidate MV may be updated to the MV and set as the final MV of the current block. Further, the process may not be performed.

The same processing may be performed in the case of performing processing in units of sub blocks.

The evaluation value is calculated by obtaining a difference value of the reconstructed image by pattern matching between a region in the reference picture corresponding to the motion vector and a predetermined region. In addition, the evaluation value may be calculated using information other than the difference value.

As the pattern matching, the 1 st pattern matching or the 2 nd pattern matching is used. The pattern 1 matching and the pattern 2 matching are called bidirectional matching (binary matching) and template matching (template matching), respectively.

In the 1 st pattern matching, pattern matching is performed between 2 blocks along a motion track (motion track) of the current block within different 2 reference pictures. Thus, in the 1 st pattern matching, as the predetermined region for calculation of the evaluation value of the candidate described above, a region within another reference picture along the motion trajectory of the current block is used.

Fig. 6 is a diagram for explaining an example of pattern matching (bidirectional matching) between 2 blocks along a motion trajectory. As shown in fig. 6, in the 1 st pattern matching, 2 motion vectors (MV0, MV1) are derived by searching for the most matched pair among pairs of 2 blocks along the motion trajectory of the current block (Cur block) and 2 blocks within different 2 reference pictures (Ref0, Ref 1). Specifically, for the current block, a difference between the reconstructed image at the specified position in the 1 st encoded reference picture (Ref0) specified by the candidate MV and the reconstructed image at the specified position in the 2 nd encoded reference picture (Ref1) specified by the symmetric MV obtained by scaling the candidate MV at the display time interval is derived, and the evaluation value is calculated using the obtained difference value. The candidate MV having the best evaluation value among the plurality of candidate MVs may be selected as the final MV.

Under the assumption of a continuous motion trajectory, the motion vectors (MV0, MV1) indicating the 2 reference blocks are proportional with respect to the temporal distance (TD0, TD1) between the current picture (Cur Pic) and the 2 reference pictures (Ref0, Ref 1). For example, when the current picture is temporally located between 2 reference pictures and the temporal distances from the current picture to the 2 reference pictures are equal, the 1 st pattern matching derives the two-directional motion vectors that are mirror-symmetric.

In the 2 nd pattern matching, pattern matching is performed between a template within the current picture, a block adjacent to the current block within the current picture (e.g., an upper and/or left adjacent block), and a block within the reference picture. Thus, in the 2 nd pattern matching, as the prescribed region for calculation of the evaluation value of the candidate described above, a block adjacent to the current block within the current picture is used.

Fig. 7 is a diagram for explaining an example of pattern matching (template matching) between the template in the current picture and the block in the reference picture. As shown in fig. 7, in the 2 nd pattern matching, a motion vector of the current block is derived by searching for a block within the reference picture (Ref0) that best matches a block adjacent to the current block (Cur block) within the current picture (Cur Pic). Specifically, the difference between the reconstructed image of the encoded region of either or both of the left-adjacent region and the top-adjacent region and the reconstructed image at the same position in the encoded reference picture (Ref0) specified by the candidate MV is derived for the current block, the evaluation value is calculated using the obtained difference value, and the candidate MV having the best evaluation value among the plurality of candidate MVs is selected as the best candidate MV.

Such information indicating whether FRUC mode is employed (e.g., referred to as a FRUC flag) is signaled at the CU level. In addition, when the FRUC mode is employed (for example, when the FRUC flag is true), information (for example, referred to as a FRUC mode flag) indicating a method of pattern matching (1 st pattern matching or 2 nd pattern matching) is signaled on the CU level. The signaling of the information is not necessarily limited to the CU level, and may be at another level (for example, a sequence level, a picture level, a slice level, a tile level, a CTU level, or a sub-block level).

Here, a mode in which a motion vector is derived based on a model assuming constant-velocity linear motion is explained. This mode is sometimes called a BIO (bi-directional optical flow).

Fig. 8 is a diagram for explaining a model assuming constant-velocity linear motion. In FIG. 8, (v)_x，v_y) Representing velocity vector, τ₀、τ₁Respectively representing a current picture (Cur Pic) and 2 reference pictures (Ref)₀，Ref₁) The distance in time between. (MVx)₀，MVy₀) Presentation and reference pictures Ref₀Corresponding motion vector, (MVx)₁，MVy₁) Presentation and reference pictures Ref₁The corresponding motion vector.

At this time, at the velocity vector (v)_x，v_y) Under the assumption of constant linear motion of (MVx)₀，MVy₀) And (MVx)₁，MVy₁) Are respectively expressed as (vx τ)₀，vyτ₀) And (-vx τ)₁，－vyτ₁) The following optical flow equation (1) holds.

[ numerical formula 1]

Here, I^(k)The luminance value of the reference image k (k is 0 or 1) after motion compensation is shown. The optical flow equation represents that the sum of (i) the temporal differential of the luminance values, (ii) the product of the velocity in the horizontal direction and the horizontal component of the spatial gradient of the reference image, and (iii) the product of the velocity in the vertical direction and the vertical component of the spatial gradient of the reference image is equal to zero. Based on a combination of the optical flow equation and a Hermite interpolation (Hermite interpolation), a motion vector in block units obtained from a merge list or the like is corrected in pixel units.

Further, the motion vector may be derived on the decoding apparatus side by a method different from the derivation of the motion vector based on the model assuming the constant velocity linear motion. For example, the motion vector may be derived in units of sub-blocks based on the motion vectors of a plurality of adjacent blocks.

Here, a mode in which a motion vector is derived in units of sub-blocks based on motion vectors of a plurality of adjacent blocks will be described. This mode is sometimes referred to as an affine motion compensation prediction (affine motion compensation prediction) mode.

Fig. 9A is a diagram for explaining derivation of a motion vector in units of sub-blocks based on motion vectors of a plurality of adjacent blocks. In fig. 9A, the current block includes 16 4 × 4 sub-blocks. Here, a motion vector v of the upper left control point of the current block is derived based on the motion vectors of the neighboring blocks₀Deriving a motion vector v for the top-right control point of the current block based on the motion vectors of the neighboring sub-blocks₁. And, 2 motion vectors v are used₀And v₁The motion vector (v) of each sub-block in the current block is derived by the following equation (2)_x，v_y)。

[ numerical formula 2]

Here, x and y represent the horizontal position and the vertical position of the subblock, respectively, and w represents a preset weight coefficient.

Such affine motion compensation prediction modes may include several modes in which the methods of deriving the motion vectors for the upper left and upper right corner control points are different. Information representing such affine motion compensated prediction modes (e.g. called affine flags) is signaled at the CU level. The signaling of the information indicating the affine motion compensation prediction mode is not necessarily limited to the CU level, and may be at another level (for example, a sequence level, a picture level, a slice level, a tile level, a CTU level, or a sub-block level).

[ prediction control section ]

The prediction control unit 128 selects either one of the intra prediction signal and the inter prediction signal, and outputs the selected signal to the subtraction unit 104 and the addition unit 116 as a prediction signal.

Here, an example of deriving a motion vector of a picture to be encoded in the merge mode will be described. Fig. 9B is a diagram for explaining an outline of the motion vector derivation process by the merge mode.

First, a predicted MV list in which candidates of predicted MVs are registered is generated. The candidates for the prediction MV include a spatial neighboring prediction MV which is an MV possessed by a plurality of coded blocks spatially located in the periphery of the coding target block, a temporal neighboring prediction MV which is an MV possessed by a block near the position of the coding target block in the coded reference picture, a combined prediction MV which is an MV generated by combining the spatial neighboring prediction MV and the MV value of the temporal neighboring prediction MV, and a zero prediction MV which is an MV having a value of zero.

Next, 1 predicted MV is selected from among the plurality of predicted MVs registered in the predicted MV list, and the MV of the encoding target block is determined.

Further, the variable length encoding unit encodes a merge _ idx, which is a signal indicating which predicted MV has been selected, by describing the merge _ idx in the stream.

The predicted MVs registered in the predicted MV list described in fig. 9B are examples, and the number of predicted MVs may be different from the number of predicted MVs in the figure, or the predicted MVs may be configured not to include some types of predicted MVs in the figure, or may be configured to add predicted MVs other than the types of predicted MVs in the figure.

Further, the final MV may be determined by performing DMVR processing described later using the MV of the encoding target block derived in the merge mode.

Here, an example of determining an MV using DMVR processing will be described.

Fig. 9C is a conceptual diagram for explaining an outline of DMVR processing.

First, the optimal MVP set for the processing target block is set as a candidate MV, and reference pixels are acquired from the 1 st reference picture, which is a processed picture in the L0 direction, and the 2 nd reference picture, which is a processed picture in the L1 direction, in accordance with the candidate MV, and a template is generated by averaging the reference pixels.

Next, using the template, the neighboring regions of the MV candidates in the 1 st reference picture and the 2 nd reference picture are searched, and the MV with the lowest cost is determined as the final MV. The cost value is calculated using a difference value between each pixel value of the template and each pixel value of the search area, an MV value, and the like.

In addition, the encoding device and the decoding device basically share the outline of the processing described here.

Note that other processing may be used as long as it is processing that can search the periphery of the candidate MV and derive the final MV, rather than the processing itself described here.

Here, a mode of generating a prediction image using LIC processing will be described.

First, an MV for acquiring a reference image corresponding to a block to be encoded from a reference picture that is an already encoded picture is derived.

Next, for the encoding target block, information indicating how the luminance value changes in the reference picture and the encoding target picture is extracted using the luminance pixel values of the left-adjacent and top-adjacent encoded peripheral reference regions and the luminance pixel value at the same position in the reference picture specified by the MV, and the luminance correction parameter is calculated.

The reference image in the reference picture specified by the MV is subjected to a luminance correction process using the luminance correction parameter, thereby generating a predicted image for the block to be encoded.

The shape of the peripheral reference region in fig. 9D is an example, and other shapes may be used.

Although the process of generating the predicted image from 1 reference picture is described here, the same applies to the case of generating the predicted image from a plurality of reference pictures, and the predicted image is generated after performing the luminance correction process on the reference images acquired from the respective reference pictures in the same manner.

As a method of determining whether or not the LIC processing is employed, for example, there is a method of using LIC _ flag which is a signal indicating whether or not the LIC processing is employed. As a specific example, the encoding apparatus determines whether or not the block to be encoded belongs to an area in which a luminance change has occurred, and encodes the block by LIC processing as LIC _ flag if the block belongs to the area in which the luminance change has occurred, and sets value 1 as LIC _ flag if the block does not belong to the area in which the luminance change has occurred, and encodes the block without LIC processing if the block is set to value 0. On the other hand, the decoding device decodes LIC _ flag described in the stream, and switches whether or not to perform the LIC processing according to the value of the flag.

As another method of determining whether or not the LIC processing is used, for example, a method of determining whether or not the LIC processing is used in the peripheral blocks is available. As a specific example, when the block to be encoded is in the merge mode, it is determined whether or not the neighboring encoded blocks selected at the time of deriving the MV in the merge mode process are encoded by the LIC process, and based on the result, whether or not the encoding is performed by the LIC process is switched. In this example, the same processing is performed in decoding.

[ overview of decoding apparatus ]

Next, an outline of a decoding apparatus capable of decoding the encoded signal (encoded bit stream) output from the encoding apparatus 100 will be described. Fig. 10 is a block diagram showing a functional configuration of decoding apparatus 200 according to embodiment 1. The decoding apparatus 200 is a moving picture/image decoding apparatus that decodes moving pictures/images in units of blocks.

As shown in fig. 10, the decoding device 200 includes an entropy decoding unit 202, an inverse quantization unit 204, an inverse transformation unit 206, an addition unit 208, a block memory 210, a loop filtering unit 212, a frame memory 214, an intra prediction unit 216, an inter prediction unit 218, and a prediction control unit 220.

The decoding apparatus 200 is realized by, for example, a general-purpose processor and a memory. In this case, when the software program stored in the memory is executed by the processor, the processor functions as the entropy decoding unit 202, the inverse quantization unit 204, the inverse transform unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220. The decoding device 200 may be realized as 1 or more dedicated electronic circuits corresponding to the entropy decoding unit 202, the inverse quantization unit 204, the inverse transform unit 206, the addition unit 208, the loop filter unit 212, the intra prediction unit 216, the inter prediction unit 218, and the prediction control unit 220.

Each component included in the decoding apparatus 200 will be described below.

[ entropy decoding section ]

The entropy decoding unit 202 entropy-decodes the encoded bit stream. Specifically, the entropy decoding unit 202 performs arithmetic decoding from the encoded bit stream into a binary signal, for example. Next, the entropy decoding unit 202 performs multi-quantization (deblocking) on the binary signal. In this way, the entropy decoding unit 202 outputs the quantized coefficients to the inverse quantization unit 204 in units of blocks.

[ inverse quantization part ]

The inverse quantization unit 204 inversely quantizes the quantized coefficient of the decoding target block (hereinafter referred to as the current block) input from the entropy decoding unit 202. Specifically, the inverse quantization unit 204 inversely quantizes the quantization coefficient of the current block based on the quantization parameter corresponding to the quantization coefficient. Then, the inverse quantization unit 204 outputs the quantized coefficient (i.e., transform coefficient) of the current block after inverse quantization to the inverse transform unit 206.

[ inverse transformation section ]

The inverse transform unit 206 performs inverse transform on the transform coefficient input from the inverse quantization unit 204 to restore the prediction error.

For example, when the information read out from the encoded bitstream indicates that EMT or AMT is used (for example, the AMT flag is true), the inverse transform unit 206 inversely transforms the transform coefficient of the current block based on the read out information indicating the transform type.

For example, when the information read out from the encoded bit stream indicates that NSST is used, the inverse transform unit 206 applies inverse retransformation to the transform coefficients.

[ addition section ]

The addition unit 208 reconstructs the current block by adding the prediction error, which is input from the inverse transform unit 206, to the prediction sample, which is input from the prediction control unit 220. The adder 208 then outputs the reconstructed block to the block memory 210 and the loop filter 212.

[ Block memory ]

The block memory 210 is a storage unit for storing a block in a picture to be decoded (hereinafter, referred to as a current picture) which is referred to in intra prediction. Specifically, the block memory 210 stores the reconstructed block output from the adder 208.

[ Cyclic Filter Unit ]

The loop filter unit 212 applies loop filtering to the block reconstructed by the adder unit 208, and outputs the filtered reconstructed block to the frame memory 214, the display device, and the like.

When the information indicating on/off of the ALF read from the encoded bit stream indicates on of the ALF, 1 filter is selected from the plurality of filters based on the direction and activity of the local gradient, and the selected filter is applied to the reconstructed block.

[ frame memory ]

The frame memory 214 is a storage unit for storing reference pictures used for inter-frame prediction, and may be referred to as a frame buffer. Specifically, the frame memory 214 stores the reconstructed block filtered by the loop filter unit 212.

[ Intra prediction Unit ]

The intra prediction unit 216 generates a prediction signal (intra prediction signal) by performing intra prediction with reference to a block in the current picture stored in the block memory 210 based on the intra prediction mode read from the coded bit stream. Specifically, the intra prediction unit 216 generates an intra prediction signal by performing intra prediction with reference to samples (for example, luminance values and color difference values) of a block adjacent to the current block, and outputs the intra prediction signal to the prediction control unit 220.

In addition, when the intra prediction mode of the reference luminance block is selected in the intra prediction of the color difference block, the intra prediction unit 216 may predict the color difference component of the current block based on the luminance component of the current block.

When the information read from the encoded bit stream indicates the use of PDPC, the intra prediction unit 216 corrects the pixel value after intra prediction based on the gradient of the reference pixel in the horizontal/vertical direction.

[ interframe prediction part ]

The inter prediction unit 218 predicts the current block with reference to the reference picture stored in the frame memory 214. Prediction is performed in units of a current block or a subblock (e.g., a 4 × 4 block) within the current block. For example, the inter prediction unit 218 performs motion compensation using motion information (e.g., a motion vector) read from the encoded bitstream, generates an inter prediction signal of the current block or sub-block, and outputs the inter prediction signal to the prediction control unit 220.

In addition, when the information read out from the encoded bitstream indicates that the OBMC mode is adopted, the inter prediction unit 218 generates an inter prediction signal using not only the motion information of the current block obtained by motion estimation but also the motion information of the neighboring block.

When the information read from the encoded bit stream indicates that the FRUC mode is adopted, the inter-frame prediction unit 218 derives motion information by performing motion estimation by a pattern matching method (bidirectional matching or template matching) read from the encoded bit stream. Then, the inter prediction unit 218 performs motion compensation using the derived motion information.

When the BIO mode is adopted, the inter-frame prediction unit 218 derives a motion vector based on a model assuming constant-velocity linear motion. Further, in the case where the information read out from the encoded bitstream indicates that the affine motion compensation prediction mode is adopted, the inter prediction section 218 derives a motion vector in a sub-block unit based on the motion vectors of the plurality of adjacent blocks.

[ prediction control section ]

The prediction control unit 220 selects either one of the intra prediction signal and the inter prediction signal, and outputs the selected signal to the adder 208 as a prediction signal.

(embodiment mode 2)

Next, embodiment 2 will be explained. In the embodiment of the present embodiment, transformation and inverse transformation will be described in detail. The configurations of the encoding device and the decoding device according to this embodiment are substantially the same as those of embodiment 1, and therefore, illustration and description thereof are omitted.

[ processing by a conversion unit and a quantization unit of an encoding device ]

First, the processing of the transform unit 106 and the quantization unit 108 in the encoding device 100 according to the present embodiment will be specifically described with reference to fig. 11. Fig. 11 is a flowchart showing the conversion and quantization processing in the encoding device 100 according to embodiment 2.

First, the transform unit 106 selects a 1 st transform base used for the encoding target block from among the candidates of the 1 st transform base having one or more bases (S101). For example, the transform unit 106 fixedly selects the transform base of DCT-II as the 1 st transform base for the encoding target block. For example, the transform unit 106 may select the 1 st transform base using the adaptive base selection mode.

The adaptive base selection mode is a mode in which a transformation base is adaptively selected from among a plurality of transformation base candidates set in advance based on a cost based on a difference between an original image and a reconstructed image and/or a code amount. This adaptive base selection mode is sometimes also referred to as EMT mode or AMT mode. As candidates for the plurality of transformation bases, for example, a plurality of transformation bases shown in fig. 6 can be used. The candidates of the plurality of transformation bases are not limited to the plurality of transformation bases in fig. 6. The plurality of candidates of the transformation base may include, for example, a transformation base equivalent to not performing the transformation.

The adaptive base selection mode and the base fixed mode can be selectively used by encoding identification information indicating which of the adaptive base selection mode and the base fixed mode using a fixed transform base (e.g., a type II DCT base) is valid within the bitstream. The identification information corresponds to identification information indicating whether the adaptive base selection mode is valid. In such a case, it may be possible to determine whether or not the 1 st transformation base matches the predetermined transformation base based on the identification information. For example, in the EMT, since there is identification information (EMT _ CU _ flag) indicating which of the adaptive base selection mode and the base fixed mode is valid in units of CU or the like, it is possible to determine whether or not the 1 st conversion base matches the predetermined conversion base using the identification information.

Then, the transform unit 106 performs 1 st transform on the residual of the block to be encoded using the 1 st transform base selected in step S102, thereby generating a 1 st transform coefficient (S102). The 1 st transformation corresponds to one transformation.

The conversion unit 106 determines whether or not the 1 st conversion base selected in step S101 matches a predetermined conversion base (S103). For example, the conversion unit 106 determines whether or not the 1 st conversion base matches any of a plurality of predetermined conversion bases. For example, the conversion unit 106 may determine whether or not the 1 st conversion base matches 1 predetermined conversion base.

As the prescribed transform base, for example, a transform base of a type II DCT (i.e., DCT-II) and/or a transform base similar thereto can be used. Such a predetermined conversion base may be defined in advance by a standard or the like. Further, for example, the prescribed transform base may be decided based on the encoding parameters and the like.

Here, when the 1 st transform base matches the predetermined transform base (yes in S103), the transform unit 106 selects a 2 nd transform base used for the encoding target block from among 1 or more 2 nd transform base candidates (S104). The transform unit 106 performs 2 nd transform on the 1 st transform coefficient using the selected 2 nd transform base, thereby generating a 2 nd transform coefficient (S105). The 2 nd transformation corresponds to a quadratic transformation. The quantization unit 108 quantizes the generated 2 nd transform coefficient (S106), and ends the transform and quantization processes.

In the 2 nd transformation, a quadratic transformation called NSST may be performed, or a transformation selectively using any one of a plurality of 2 nd transformation base candidates may be performed. In this case, the selected transform base may be fixed in the selection of the 2 nd transform base. That is, a predetermined fixed conversion base may be selected as the 2 nd conversion base. As the 2 nd transformation basis, a transformation basis equivalent to not performing the 2 nd transformation may also be used.

NSST may be DCT or post-DST frequency-space transform. For example, NSST may be KLT (Karhunen Loeve Transform, K-L Transform) for DCT or DST Transform coefficients obtained off-line, or may be HyGT (Hypercube-Givens Transform, H-G Transform) expressed by a combination of rotational transforms.

On the other hand, when the 1 st transformation basis is different from the predetermined transformation basis (no in S103), the transformation unit 106 skips the selection step (S104) of the 2 nd transformation basis and the 2 nd transformation step (S105). That is, the conversion unit 106 does not perform the 2 nd conversion. In this case, the 1 st transform coefficient generated in step S207 is quantized (S106), and the transform and quantization processing ends.

When the 2 nd transform step is skipped in this way, information indicating that the 2 nd transform is not to be performed may be notified to the decoding apparatus. When the 2 nd transform step is skipped, the 2 nd transform may be performed using a 2 nd transform basis equivalent to the case where the transform is not performed, and information indicating the 2 nd transform basis may be notified to the decoding apparatus.

The inverse quantization unit 112 and the inverse transform unit 114 of the encoding device 100 can reconstruct the encoding target block by performing a process reverse to the process performed by the transform unit 106 and the quantization unit 108.

[ processing by the inverse quantization unit and inverse transformation unit of the decoding apparatus ]

Next, the processing performed by the inverse quantization unit 204 and the inverse transform unit 206 of the decoding device 200 according to the present embodiment will be specifically described with reference to fig. 12. Fig. 12 is a flowchart showing inverse quantization and inverse transform processing in decoding apparatus 200 according to embodiment 2.

First, the inverse quantization unit 204 inversely quantizes the quantization coefficient of the decoding target block (S601). The inverse transform unit 206 determines whether or not the 1 st inverse transform basis used for the decoding target block matches a predetermined inverse transform basis (S602). As the predetermined inverse transform base, an inverse transform base corresponding to the predetermined transform base used in the encoding apparatus 100 is used.

When the 1 st inverse transform base matches the predetermined inverse transform base (yes in S602), the inverse transform unit 206 selects the 2 nd inverse transform base used for the decoding target block (S603). Selecting an inverse transform base (1 st inverse transform base or 2 nd inverse transform base) in decoding apparatus 200 means determining an inverse transform base based on predetermined information. As the predetermined information, for example, a base selection signal can be used. The predetermined information may be an intra prediction mode or a block size.

The inverse transform unit 206 performs 2 nd inverse transform on the inversely quantized coefficients of the decoding target block using the selected 2 nd inverse transform basis, thereby generating 2 nd inverse transform coefficients (S604). Further, the inverse transform unit 206 selects the 1 st inverse transform base (S605). The inverse transform unit 206 performs the 1 st inverse transform on the 2 nd inverse transform coefficient generated in step S605 using the selected 1 st inverse transform base (S606), and ends the inverse quantization and inverse transform processing.

On the other hand, when the 1 st inverse transform base is different from the predetermined inverse transform base (no in S602), the inverse transform unit 206 skips the selection step (S603) of the 2 nd inverse transform base and the 2 nd inverse transform step (S604). That is, the inverse transform unit 206 selects the 1 st inverse transform base without performing the 2 nd inverse transform (S605). The inverse transform unit 206 performs 1 st inverse transform on the coefficient inversely quantized in step S501 using the selected 1 st inverse transform base (S606), and ends the inverse quantization and inverse transform processing.

[ Effect and the like ]

The inventors have found the following problems: in conventional encoding, the amount of processing for searching for an optimal combination of a transform base and a transform parameter (for example, a coefficient of a filter) is enormous in both the 1 st transform and the 2 nd transform. In contrast, according to the encoding device 100 and the decoding device 200 according to the present embodiment, the 2 nd transform can be skipped from the 1 st transform basis. As a result, the processing for searching for the optimal combination of the transformation basis and the transformation parameter in both the 1 st transformation and the 2 nd transformation can be reduced, and the processing load can be reduced while suppressing the reduction in compression efficiency.

As described above, according to the encoding device 100 and the decoding device 200 according to the present embodiment, when the 1 st transform base is different from the predetermined transform base, the 2 nd transform can be skipped. The 1 st transform coefficient generated by the 1 st transform is affected by the 1 st transform base. Therefore, the effect of improving the compression rate by performing the 2 nd transform on the 1 st transform coefficient depends on the 1 st transform base in many cases. Therefore, by skipping the 2 nd transform when the 1 st transform base is different from the predetermined transform base having a high effect of improving the compression rate, it is possible to reduce the processing load while suppressing a decrease in compression efficiency.

In particular, in the type II DCT, the density of the low frequency is often increased, and therefore the effect of the 2 nd transform is likely to be increased. Therefore, by using the base of the type II DCT as the predetermined transform base, the 2 nd transform is performed when the effect of improving the compression efficiency by the 2 nd transform is large, and the 2 nd transform is skipped if not, whereby it can be expected to further reduce the processing load while suppressing the reduction in the compression efficiency.

The above processing can be applied to either of the luminance signal and the color difference signal, and can be applied to each signal of R, G, B as long as the input signal is in the RGB format. Further, the selectable basis in the 1 st conversion or the 2 nd conversion may be different between the luminance signal and the color difference signal. For example, the frequency band of the luminance signal is wide compared to the color difference signal. Therefore, it is possible to select more kinds of bases than color differences in the conversion of the luminance signal.

The predetermined conversion base is not limited to 1 conversion base. That is, the predetermined transformation base may be a plurality of transformation bases. In such a case, it is sufficient to determine whether or not the 1 st conversion base matches any of the plurality of predetermined conversion bases.

This embodiment can be implemented in combination with at least some of the other embodiments of the present invention. Further, a part of the processing, a part of the configuration of the apparatus, a part of the syntax, and the like described in the flowchart of the present embodiment may be combined with other embodiments to be implemented.

(embodiment mode 3)

Next, embodiment 3 will be explained. The present embodiment differs from embodiment 2 in that the transform process differs depending on whether or not intra prediction is used for the block to be encoded/decoded. Hereinafter, the present embodiment will be described mainly with reference to the drawings, focusing on differences from embodiment 2 described above. In the following drawings, steps substantially the same as those in embodiment 2 are denoted by the same reference numerals, and redundant description thereof will be omitted or simplified.

First, the processing of the transform unit 106 and the quantization unit 108 in the encoding device 100 according to the present embodiment will be specifically described with reference to fig. 13. Fig. 13 is a flowchart showing the conversion and quantization processing in the encoding device 100 according to embodiment 3.

First, the transform unit 106 determines which of intra prediction and inter prediction is used for the block to be encoded (S201). For example, the conversion unit 106 determines which of the intra prediction and the inter prediction is used based on the cost based on the difference between the original image and the reconstructed image obtained by locally decoding the compressed image and/or the cost of the code amount. Further, for example, the transformation unit 106 may determine which of intra prediction and inter prediction is used based on information (for example, a picture type) different from the cost based on the difference and/or the amount of code.

Here, when it is determined that inter prediction is used for the block to be encoded (inter in S201), the transform unit 106 selects the 1 st transform base used for the block to be encoded from among 1 or more 1 st transform base candidates (S202). For example, the transform unit 106 fixedly selects the transform base of DCT-II as the 1 st transform base for the encoding target block. For example, the transform unit 106 may select the 1 st transform base from among a plurality of 1 st transform base candidates.

Then, the transform unit 106 performs 1 st transform on the residual of the block to be encoded using the 1 st transform base selected in step S202, thereby generating a 1 st transform coefficient (S203). The quantization unit 108 quantizes the generated 1 st transform coefficient (S204), and ends the transform and quantization processes.

On the other hand, when it is determined that intra prediction is to be used for the block to be encoded (in the frame of S201), the conversion unit 106 performs steps S101 to S105 in the same manner as in embodiment 2. Then, the quantization unit 108 quantizes the 1 st transform coefficient generated in step S102 or the 2 nd transform coefficient generated in step S105 (S204), and ends the transform and quantization processing.

Next, the processing performed by the inverse quantization unit 204 and the inverse transform unit 206 of the decoding device 200 according to the present embodiment will be specifically described with reference to fig. 14. Fig. 14 is a flowchart showing inverse quantization and inverse transform processing in decoding apparatus 200 according to embodiment 3.

First, the inverse quantization unit 204 inversely quantizes the quantization coefficient of the decoding target block (S601). The inverse transform unit 206 determines which of intra prediction and inter prediction is used for the block to be decoded (S701). For example, the inverse transform unit 206 determines which of intra prediction and inter prediction is used based on information obtained from the bitstream.

When it is determined that inter prediction is to be used for the decoding target block (inter in S701), the inverse transform unit 206 selects the 1 st inverse transform basis for the decoding target block (S702). The inverse transform unit 206 performs 1 st inverse transform on the inversely quantized coefficients of the decoding target block using the 1 st inverse transform basis selected in step S503 (S703), and ends the inverse quantization and inverse transform processes.

On the other hand, when it is determined that intra prediction is used for the decoding target block (in the frame of S701), the inverse transform unit 206 executes steps S602 to S606 in the same manner as in embodiment 2, and ends the inverse quantization and inverse transform processing.

[ Effect and the like ]

According to the encoding device 100 and the decoding device 200 of the present embodiment, the 2 nd transform can be skipped in accordance with the intra/inter prediction and the 1 st transform basis. As a result, the processing for searching for the optimum combination of the conversion base and the conversion parameter in both the 1 st conversion and the 2 nd conversion can be reduced, and the processing load can be reduced while suppressing the reduction in compression efficiency.

(embodiment mode 4)

Next, embodiment 4 will be explained. The present embodiment differs from embodiments 2 and 3 in that the transform process differs depending on the intra prediction mode of the block to be encoded/decoded. Hereinafter, the present embodiment will be described mainly with reference to the drawings, focusing on differences from embodiments 2 and 3 described above. In the following drawings, steps substantially the same as those in embodiment 2 or embodiment 3 are denoted by the same reference numerals, and redundant description is omitted or simplified.

First, the processing of the transform unit 106 and the quantization unit 108 in the encoding device 100 according to the present embodiment will be specifically described with reference to fig. 15. Fig. 15 is a flowchart showing the conversion and quantization processing in the encoding device 100 according to embodiment 4.

The transform unit 106 determines which of intra prediction and inter prediction is used for the block to be encoded, as in embodiment 2 (S201). Here, when it is determined that inter prediction is used for the block to be encoded (inter frame in S201), the conversion unit 106 performs step S202 and step S203 in the same manner as in embodiment 2. The quantization unit 108 quantizes the 1 st transform coefficient generated in step S203 (S302).

On the other hand, when it is determined that intra prediction is to be used for the block to be encoded (in the frame of S201), the conversion unit 106 performs step S101 and step S102 in the same manner as in embodiment 1. Then, the transform unit 106 determines whether or not the intra prediction mode of the block to be encoded is a predetermined mode (S106). For example, the conversion unit 106 determines whether or not the intra prediction mode is a predetermined mode based on a cost based on the difference between the original image and the reconstructed image and/or the amount of code. The determination as to whether or not the intra prediction mode is the predetermined mode may be based on information different from the cost.

The predetermined pattern may be defined in advance by, for example, a standard specification. For example, the predetermined mode may be determined based on an encoding parameter or the like. As the predetermined mode, for example, a directional prediction mode in an oblique direction can be used.

The directional prediction mode is an intra prediction mode in which a specific direction is used for prediction of a block to be encoded. In the directional prediction mode, the pixel value is predicted by extending the value of the reference pixel in a specific direction. The pixel value is a value in a pixel unit constituting a picture, and is, for example, a luminance value or a color difference value. For example, the directional prediction mode is an intra prediction mode other than the DC prediction mode and the Planar prediction mode.

The directional prediction mode in the oblique direction refers to a directional prediction mode having a direction oblique to the horizontal direction and the vertical direction. For example, the diagonal directional prediction mode may be a 3-directional prediction mode recognized at 2 (lower left), 34 (upper left), and 66 (upper right) among 65-directional prediction modes recognized by numbers of 2 to 66 in order from lower left to upper right (see fig. 5A). For example, the directional prediction mode in the diagonal direction may be a directional prediction mode in 7 directions recognized at 2 to 3 (lower left), 33 to 35 (upper left), and 65 to 66 (upper right) among the directional prediction modes in the 65 direction.

When the intra prediction mode is not the predetermined mode (no in S301), the conversion unit 106 determines whether or not the 1 st conversion base selected in step S101 matches the predetermined conversion base (S103).

When the intra prediction mode is the predetermined mode (yes in S301), or when the 1 st transform base matches the predetermined transform base (yes in S103), the transform unit 106 selects the 2 nd transform base for the encoding target block from among 1 or more 2 nd transform base candidates (S104). The transform unit 106 performs 2 nd transform on the 1 st transform coefficient using the selected 2 nd transform base, thereby generating a 2 nd transform coefficient (S105). The quantization unit 108 quantizes the generated 2 nd transform coefficient (S302), and ends the transform and quantization processes.

When the intra prediction mode is different from the predetermined mode (no in S301) and the 1 st transform base is different from the predetermined transform base (no in S103), the transform unit 106 skips the selection step (S104) of the 2 nd transform base and the 2 nd transform step (S105). That is, the conversion unit 106 does not perform the 2 nd conversion. In this case, the 1 st transform coefficient generated in step S102 is quantized (S302), and the transform and quantization processing ends.

Next, the processing performed by the inverse quantization unit 204 and the inverse transform unit 206 of the decoding device 200 according to the present embodiment will be specifically described with reference to fig. 16. Fig. 16 is a flowchart showing inverse quantization and inverse transform processing in decoding apparatus 200 according to embodiment 4.

First, the inverse quantization unit 204 inversely quantizes the quantization coefficient of the decoding target block (S601). The inverse transform unit 206 determines which of intra prediction and inter prediction is used for the block to be decoded (S701).

When it is determined that inter prediction is used for the decoding target block (inter in S701), the inverse transform unit 206 executes step S702 and step S703 in the same manner as in embodiment 3, and ends the inverse quantization and inverse transform processing.

On the other hand, when it is determined that intra prediction is to be used for the decoding target block (in the frame of S701), the inverse transform unit 206 determines whether or not the intra prediction mode of the decoding target block is a predetermined mode (S801). The predetermined pattern used in the decoding apparatus 200 is the same as the predetermined pattern used in the encoding apparatus 100.

When the intra prediction mode is not the predetermined mode (no in S801), the inverse transform unit 206 determines whether or not the 1 st inverse transform base used for the decoding target block matches the predetermined inverse transform base (S602).

If the intra prediction mode is the predetermined mode (yes in S801) or if the 1 st inverse transform base matches the predetermined inverse transform base (yes in S602), step S603 to step S606 are executed in the same manner as in embodiment 2, and the inverse quantization and inverse transform processing are terminated.

On the other hand, when the intra prediction mode is different from the predetermined mode (no in S801) and the 1 st inverse transform base is different from the predetermined inverse transform base (no in S602), the inverse transform unit 206 skips the selection step of the 2 nd inverse transform base (S603) and the 2 nd inverse transform step (S604). That is, the inverse transform unit 206 selects the 1 st inverse transform base without performing the 2 nd inverse transform (S605). The inverse transform unit 206 performs 1 st inverse transform on the coefficient inversely quantized in step S501 using the selected 1 st inverse transform base (S606), and ends the inverse quantization and inverse transform processing.

[ Effect and the like ]

As described above, according to encoding apparatus 100 and decoding apparatus 200 according to the present embodiment, it is possible to skip the 2 nd transform according to the intra prediction mode and the 1 st transform basis. As a result, the processing for searching for the optimum combination of the conversion base and the conversion parameter in both the 1 st conversion and the 2 nd conversion can be reduced, and the processing load can be reduced while suppressing the reduction in compression efficiency.

In particular, if the diagonal directional prediction mode is used as the predetermined mode, the 2 nd transform is performed when the diagonal directional prediction mode is used for the encoding/decoding target block, and the 2 nd transform can be skipped in other cases. This can reduce the processing load while suppressing a decrease in compression efficiency.

Generally, in the 1 st transform, DCT or DST that can be separated in the vertical direction and the horizontal direction is performed. In such a case, correlation in the oblique direction is not used in the 1 st transformation. Therefore, in the case of using a directional prediction mode in an oblique direction in which the correlation in the oblique direction is high, it is difficult to sufficiently integrate coefficients only with the 1 st transform. Therefore, when the directional prediction mode in the diagonal direction is used for the intra prediction, the coefficients can be further condensed by performing the 2 nd transform using the 2 nd transform base using the correlation in the diagonal direction, and the compression efficiency can be improved.

The order of steps in the flowcharts of fig. 15 and 16 is not limited to the order shown in fig. 15 and 16. For example, in fig. 15, the step of determining whether the intra prediction mode is the predetermined mode (S801) and the step of determining whether the 1 st transform base matches the predetermined transform base (S602) may be performed in reverse order or simultaneously.

(embodiment 5)

Next, embodiment 5 will be explained. In the embodiment of the present embodiment, the encoding and decoding of information related to transformation and inverse transformation will be described. Hereinafter, the present embodiment will be described mainly with reference to the drawings, focusing on differences from embodiments 2 to 4 described above. In the present embodiment, the transformation and quantization processing, and the inverse quantization and inverse transformation processing are substantially the same as those in embodiment 4, and therefore, the description thereof is omitted.

[ processing by the entropy encoding section of the encoding apparatus ]

The encoding process of the information related to the conversion by the entropy encoding unit 110 in the encoding device 100 according to the present embodiment will be specifically described with reference to fig. 17. Fig. 17 is a flowchart showing an encoding process in the encoding device 100 according to embodiment 5.

When inter prediction is used for the block to be encoded (inter in S401), the entropy encoding unit 110 encodes the 1 st base selection signal into the bit stream (S402). Here, the 1 st base selection signal is information or data indicating the 1 st transformation base selected in step S202 of fig. 15.

Encoding a signal within a bitstream means that a code representing information is arranged within the bitstream. For example, the code is generated by Context Adaptive Binary Arithmetic Coding (CABAC). In addition, in the generation of the code, it is not necessary to use CABAC, and entropy coding is not necessary. For example, the code may be the information itself (e.g., a flag of 0 or 1).

Next, the entropy encoding unit 110 encodes the coefficients quantized in step S302 of fig. 15 (S403), and ends the encoding process.

When intra prediction is used for the block to be encoded (intra in S401), the entropy encoding unit 110 encodes an intra prediction mode signal indicating the intra prediction mode of the block to be encoded into the bitstream (S404). The entropy encoding unit 110 encodes the 1 st base selection signal into a bit stream (S405). Here, the 1 st base selection signal is information or data indicating the 1 st conversion base selected in step S101 of fig. 15.

Here, when the 2 nd transform is performed (yes in S406), the entropy encoding unit 110 encodes the 2 nd base selection signal into the bit stream (S407). Here, the 2 nd base selection signal is information or data indicating the 2 nd conversion base selected in step S104. On the other hand, when the 2 nd transform is not performed (no in S406), the entropy encoding unit 110 skips the encoding step of the 2 nd base selection signal (S407). That is, the entropy encoding unit 110 does not encode the 2 nd base selection signal.

Finally, the entropy encoding unit 110 encodes the coefficients quantized in step S302 (S408), and ends the encoding process.

[ grammar ]

Fig. 18 shows a specific example of the syntax in embodiment 5.

In fig. 18, a prediction mode signal (pred _ mode), an intra prediction mode signal (pred _ mode _ dir), and an adaptive selection mode signal (emt _ mode) are encoded in a bitstream together with a primary _ transform _ type 1-th base selection signal and a secondary _ transform _ type 2-th base selection signal as necessary.

The prediction mode signal (pred _ mode) indicates which of intra prediction and inter prediction is used in the encoding/decoding target block (here, coding unit). The inverse transform unit 206 of the decoding device 200 can determine whether or not intra prediction is used for the decoding target block based on the prediction mode signal.

The intra prediction mode signal (pred _ mode _ dir) indicates an intra prediction mode in the case where intra prediction is used for the encoding/decoding target block. The inverse transform unit 206 of the decoding device 200 can determine whether or not the intra prediction mode of the decoding target block is a predetermined mode based on the intra prediction mode signal.

The adaptive selection mode signal (emt _ mode) indicates whether an adaptive base selection mode for adaptively selecting a transform base from among a plurality of candidates of transform bases is used in the encoding/decoding target block. Here, in the case where the adaptive selection mode signal is "on", the transform base is selected from among the DCT of type V, the DCT of type VIII, the DST of type I, and the DST of type VII. Conversely, in the case where the adaptive selection mode signal is "off," a type II DCT is selected. The inverse transform unit 206 of the decoding device 200 can determine whether or not the 1 st inverse transform basis of the decoding target block matches a predetermined inverse transform basis based on the adaptive selection mode signal.

The 1 st base selection signal (primary _ transform _ type) represents a 1 st transform base/inverse transform base used for transform/inverse transform of the encoding/decoding object block. In the case where the adaptive selection mode signal is "on", the 1 st base selection signal is encoded into the bitstream. Conversely, in the case where the adaptive selection mode signal is "off," the base 1 selection signal is not encoded. The inverse transform unit 206 of the decoding device 200 can select the 1 st inverse transform basis based on the 1 st basis selection signal.

The 2 nd base selection signal (second _ transform _ type) represents a 2 nd transform base/inverse transform base used for transform/inverse transform of the encoding/decoding object block. In case that the adaptive selection mode signal is "on" and the intra prediction mode signal is "2", "34", or "66", the 2 nd base selection signal is encoded into the bitstream. "2", "34", and "66" of the intra prediction mode signal each indicate a directional prediction mode in a diagonal direction. That is, in the case where the 1 st transform basis coincides with the basis of the type II DCT and the intra prediction mode is the directional prediction mode in the diagonal direction, the 2 nd basis selection signal is encoded into the bitstream. In contrast, in the case where the intra prediction mode is not the directional prediction mode in the diagonal direction, the 2 nd base selection signal is not encoded into the bitstream. The inverse transform unit 206 of the decoding device 200 can select the 2 nd inverse transform basis based on the 2 nd basis selection signal.

Here, as the transformation bases that can be selected in the adaptive base selection mode, bases of the DCT of type V, the DCT of type VIII, the DST of type I, and the DST of type VII are used, but the present invention is not limited thereto. For example, instead of the DCT of type V, a DCT of type IV may be used. In the DCT of type IV, part of the processing of the DCT of type II can be appropriated, and thus the processing load can be reduced. In addition, DST of type IV may also be used. The DST of type IV can steal a part of the processing of the DCT of type IV, and thus can realize reduction of the processing load.

[ processing by an entropy decoding unit of a decoding apparatus ]

Next, the processing of the entropy decoding unit 202 of the decoding device 200 according to the present embodiment will be specifically described with reference to fig. 19. Fig. 19 is a flowchart showing a decoding process in decoding apparatus 200 according to embodiment 5.

When inter prediction is used for the block to be decoded (inter in S901), the entropy decoding unit 202 decodes the 1 st base selection signal from the bitstream (S902).

Decoding a signal from a bit stream means reading a code representing information from the bit stream and recovering the information from the read code. The restoration from code to information uses, for example, context-adaptive binary arithmetic decoding (CABAD). In addition, in the restoration from the code to the information, it is not necessary to use CABAD and entropy decoding. For example, when the read code itself indicates information (for example, a flag of 0 or 1), only the code may be read.

Next, the entropy decoding unit 202 decodes the quantized coefficient from the bit stream (S903), and ends the decoding process.

When intra prediction is used for the block to be decoded (intra in S901), the entropy decoding unit 202 decodes an intra prediction mode signal from the bitstream (S904). Further, the entropy decoding section 202 decodes the 1 st base selection signal from the bit stream (S905).

Here, when the 2 nd inverse transform is performed (yes in S906), the entropy decoding unit 202 decodes the 2 nd base selection signal from the bitstream (S907). On the other hand, when the 2 nd inverse transform is not performed (no in S906), the entropy decoding unit 202 skips the decoding step of the 2 nd base selection signal (S907). That is, the entropy decoding unit 202 does not decode the 2 nd base selection signal.

Finally, the entropy decoding unit 202 decodes the quantized coefficient from the bit stream (S908), and ends the decoding process.

[ Effect and the like ]

As described above, according to the encoding device 100 and the decoding device 200 according to the present embodiment, the 1 st base selection signal and the 2 nd base selection signal can be encoded in the bit stream. Then, by encoding the intra prediction mode signal and the 1 st base selection signal before the 2 nd base selection signal, it is possible to determine whether or not to skip the 2 nd inverse transform before decoding the 2 nd base selection signal. Therefore, even when the 2 nd inverse transform is skipped, the encoding of the 2 nd base selection signal can be skipped, and the compression efficiency can be improved.

(embodiment mode 6)

Next, embodiment 6 will be explained. The embodiment of the present embodiment differs from embodiment 5 described above in that information indicating an intra prediction mode in which the 2 nd transform is performed is encoded. Hereinafter, the present embodiment will be described mainly with reference to the drawings, focusing on differences from embodiment 5 described above. In the following drawings, steps substantially the same as those in embodiment 5 are denoted by the same reference numerals, and redundant description thereof will be omitted or simplified.

[ processing by the entropy encoding section of the encoding apparatus ]

The encoding process of the information related to the conversion by the entropy encoding unit 110 in the encoding device 100 according to the present embodiment will be specifically described with reference to fig. 20. Fig. 20 is a flowchart showing an encoding process in the encoding device 100 according to embodiment 6.

When inter prediction is used for the block to be encoded (inter in S401), the entropy encoding unit 110 executes step S402 and step S403 to end the encoding process in the same manner as in embodiment 5.

On the other hand, when intra prediction is used for the block to be encoded (intra in S401), the entropy encoding unit 110 encodes the 2 nd conversion target prediction mode signal into the bitstream (S501). The 2 nd conversion target prediction mode signal indicates a predetermined mode for determining whether or not to perform the 2 nd inverse conversion. Specifically, the 2 nd conversion target prediction mode signal indicates, for example, the number of the intra prediction mode (for example, 2, 34, and 66).

The Coding Unit of the 2 nd conversion target prediction mode signal may be CU (Coding Unit) or CTU (Coding Tree Unit) Unit, or may be SPS (Sequence Parameter Set) or PPS (Picture Parameter Set) or slice Unit corresponding to the h.265/HEVC standard.

Thereafter, the entropy encoding unit 110 executes steps S404 to S408 in the same manner as in embodiment 5, and ends the encoding process.

[ processing by an entropy decoding unit of a decoding apparatus ]

Next, the processing of the entropy decoding unit 202 of the decoding device 200 according to the present embodiment will be specifically described with reference to fig. 21. Fig. 21 is a flowchart showing a decoding process in decoding apparatus 200 according to embodiment 6.

When inter prediction is used for the block to be decoded (inter frame in S901), the entropy decoding unit 202 executes step S902 and step S903 and terminates the decoding process in the same manner as in embodiment 5.

On the other hand, when intra prediction is used for the decoding target block (intra in S901), the entropy decoding unit 202 decodes the 2 nd conversion target prediction mode signal from the bitstream (S1001).

Thereafter, the entropy decoding unit 202 executes steps S904 to S908 in the same manner as in embodiment 5, and terminates the decoding process.

[ Effect and the like ]

As described above, according to the encoding device 100 and the decoding device 200 according to the present embodiment, it is possible to encode the 2 nd transform target prediction mode signal indicating the predetermined mode as the intra prediction mode in which the 2 nd transform and the inverse transform are performed into the bitstream. Therefore, the encoding device 100 can arbitrarily determine the predetermined pattern, and the compression efficiency can be improved.

Further, the order of encoding the signals may be determined in advance, and the signals may be encoded in an order different from the order of encoding.

(embodiment 7)

Various modifications may be made to embodiments 2 to 6.

For example, in each of the above embodiments, the 1 st transformation base may be fixed according to the size of the encoding/decoding target block. For example, in the case where the block size is smaller than a certain size (e.g., 4 × 4 pixels, 4 × 8 pixels, or 8 × 4 pixels), the 1 st transform base is fixed to the transform base of the DST of type VII, and the encoding of the 1 st base selection signal may be skipped at this time.

For example, in each of the above embodiments, a signal indicating whether or not the process of selecting the 1 st transform base and the 1 st transform or skipping the selection of the 2 nd transform base and the 2 nd transform is effective may be encoded. For example, if the process of skipping the 2 nd transform is valid, the 2 nd base selection signal may not be encoded, and therefore the decoding operation is different from the case where the skipping of the 2 nd transform is invalid. The coding units of such signals may be cu (coding unit) or ctu (coding Tree unit) units, or sps (sequence Parameter set) or pps (picture Parameter set) and slice units corresponding to the h.265/HEVC standard.

For example, in each of the above embodiments, based on the picture type (I, P, B), the slice type (I, P, B), the block size, the number of non-zero coefficients, the quantization parameter, and the Temporal _ id (layer of hierarchical coding), the selection of the 1 st transform base and the 1 st transform may be skipped, or the selection of the 2 nd transform base and the 2 nd transform may be skipped.

When the encoding device performs the above-described operation, the decoding device also performs a corresponding operation. For example, when information indicating whether or not the process of skipping the 1 st transform or the 2 nd transform is valid is encoded, the decoding device decodes the information, and determines whether or not the 1 st transform or the 2 nd transform is valid and whether or not the 1 st base selection signal or the 2 nd base selection signal is encoded.

In embodiments 5 and 6, a plurality of signals (for example, an intra prediction mode signal, an adaptive selection mode signal, a 1 st base selection signal, and a 2 nd base selection signal) are encoded in a bit stream, but in embodiments 2 to 4, these plurality of signals may not be encoded in the bit stream. For example, these plurality of signals may be notified to the decoding apparatus 200 from the encoding apparatus 100 different from the bit string.

In the present embodiment, the positions in the bit streams of the plurality of signals (for example, the intra prediction mode signal, the adaptive selection mode signal, the 1 st base selection signal, and the 2 nd base selection signal) are not particularly limited. The plurality of signals are encoded, for example, into at least one of a plurality of headers. As the plurality of headers, for example, a video parameter set, a sequence parameter set, a picture parameter set, and a slice header can be used. Furthermore, in the case where signals are in multiple levels (e.g., picture parameter sets and slice headers), signals in a lower level (e.g., slice header) overwrite signals in a higher level (e.g., picture parameter sets).

(embodiment mode 8)

In the above embodiments and modifications, each functional block can be realized by an MPU, a memory, and the like in general. The processing of each functional block is usually realized by reading out and executing software (program) recorded in a recording medium such as a ROM by a program execution unit such as a processor. The software may be distributed by downloading or the like, or may be distributed by recording the software in a recording medium such as a semiconductor memory. It is needless to say that each functional block can be realized by hardware (dedicated circuit).

Note that the processing described in the embodiment and each modification may be realized by collective processing using a single device (system), or may be realized by distributed processing using a plurality of devices. The processor that executes the program may be single or plural. That is, the collective processing may be performed or the distributed processing may be performed.

The present invention is not limited to the above embodiments, and various modifications can be made, and they are also included in the scope of the present invention.

Further, an application example of the moving image encoding method (image encoding method) or the moving image decoding method (image decoding method) shown in the above-described embodiment and each modification and a system using the same will be described. The system is characterized by comprising an image encoding device using an image encoding method, an image decoding device using an image decoding method, and an image encoding and decoding device provided with both. Other configurations in the system can be changed as appropriate depending on the case.

[ use example ]

Fig. 22 is a diagram showing the overall configuration of a content providing system ex100 that realizes a content distribution service. The area for providing the communication service is divided into desired sizes, and base stations ex106, ex107, ex108, ex109, and ex110 as fixed radio stations are provided in each cell.

In the content providing system ex100, devices such as a computer ex111, a game machine ex112, a camera ex113, a home appliance ex114, and a smart phone ex115 are connected to the internet ex101 via the internet service provider ex102, the communication network ex104, and the base stations ex106 to ex 110. The content providing system ex100 may be connected by combining some of the above elements. The devices may be directly or indirectly connected to each other via a telephone network, short-range wireless, or the like without via the base stations ex106 to ex110 as fixed wireless stations. The streaming server ex103 is connected to devices such as the computer ex111, the game machine ex112, the camera ex113, the home appliance ex114, and the smart phone ex115 via the internet ex101 and the like. The streaming server ex103 is connected to a terminal or the like in a hot spot in the airplane ex117 via the satellite ex 116.

Instead of the base stations ex106 to ex110, a wireless access point, a hot spot, or the like may be used. The streaming server ex103 may be directly connected to the communication network ex104 without via the internet ex101 or the internet service provider ex102, or may be directly connected to the airplane ex117 without via the satellite ex 116.

The camera ex113 is a device such as a digital camera capable of shooting still images and moving images. The smart phone ex115 is a smart phone, a mobile phone, or a phs (personal Handyphone system) that is compatible with a mobile communication system generally called 2G, 3G, 3.9G, 4G, or 5G in the future.

The home appliance ex118 is a refrigerator, a device included in a home fuel cell cogeneration system, or the like.

In the content providing system ex100, a terminal having a camera function is connected to the streaming server ex103 via the base station ex106 or the like, and live distribution or the like is possible. In live distribution, the terminals (such as the computer ex111, the game machine ex112, the camera ex113, the home appliance ex114, the smartphone ex115, and the terminal in the airplane ex 117) perform the encoding processing described in the above-described embodiment and the modifications on the still image or moving image content captured by the user using the terminals, multiplex video data obtained by encoding and audio data obtained by encoding audio corresponding to the video, and transmit the obtained data to the streaming server ex 103. That is, each terminal functions as an image coding apparatus according to an aspect of the present invention.

On the other hand, the streaming server ex103 distributes the streaming of the content data transmitted to the client having the request. The client is a terminal or the like in the computer ex111, the game machine ex112, the camera ex113, the home appliance ex114, the smart phone ex115, or the airplane ex117, which can decode the data subjected to the encoding processing. Each device that receives the distributed data performs decoding processing on the received data and reproduces it. That is, each device functions as an image decoding apparatus according to an aspect of the present invention.

[ Dispersion treatment ]

The streaming server ex103 may be a plurality of servers or a plurality of computers, and distribute data by distributed processing or recording. For example, the streaming server ex103 may be implemented by cdn (contents Delivery network), and content Delivery is implemented by a network connecting a plurality of edge servers distributed in the world and the edge servers. In a CDN, edge servers that are physically close are dynamically allocated according to clients. Furthermore, by caching and distributing content to the edge server, latency can be reduced. Further, when some error occurs or when the communication state changes due to an increase in traffic or the like, the processing can be distributed by a plurality of edge servers, or the distribution can be continued by switching the distribution subject to another edge server or by bypassing the network portion in which the failure has occurred.

Further, the encoding process of the captured data may be performed by each terminal, may be performed on the server side, or may be performed by sharing each other, without being limited to the distributed process of the distribution itself. As an example, the encoding process is generally performed 2 processing cycles. The complexity or the amount of code of an image of a frame or scene unit is detected in the 1 st loop. In addition, in the 2 nd cycle, the processing for improving the encoding efficiency by maintaining the image quality is performed. For example, by performing the encoding process for the 1 st time by the terminal and performing the encoding process for the 2 nd time by the server side that receives the content, it is possible to improve the quality and efficiency of the content while reducing the processing load in each terminal. In this case, if there is a request to receive and decode data in substantially real time, the data that has been encoded for the first time by the terminal can be received and reproduced by another terminal, and therefore, more flexible real-time distribution is possible.

As another example, the camera ex113 or the like performs feature amount extraction from an image, compresses data on feature amounts as metadata, and transmits the compressed data to the server. The server judges the importance of the target based on the feature amount, switches quantization accuracy, and the like, and performs compression corresponding to the meaning of the image. The feature data is particularly effective for improving the accuracy and efficiency of motion vector prediction at the time of recompression in the server. Further, the terminal may perform simple coding such as VLC (variable length coding), and the server may perform coding with a large processing load such as CABAC (context adaptive binary arithmetic coding).

As another example, in a stadium, a shopping mall, a factory, or the like, a plurality of terminals may capture a plurality of pieces of video data of substantially the same scene. In this case, a plurality of terminals that have performed image capturing and, if necessary, other terminals and servers that have not performed image capturing are used, and the encoding process is assigned and distributed in units of, for example, gops (group of picture), pictures, or tiles obtained by dividing pictures. Thus, delay can be reduced and real-time performance can be improved.

Further, since the plurality of pieces of video data are substantially the same scene, the server may manage and/or instruct the plurality of pieces of video data so as to refer to the pieces of video data captured by the respective terminals. Alternatively, the server may receive encoded data from each terminal, change the reference relationship among a plurality of data, or re-encode the picture itself by correcting or replacing the picture. This enables generation of a stream in which the quality and efficiency of individual data are improved.

The server may also transcode the video data to change the encoding method of the video data and distribute the video data. For example, the server may convert an MPEG encoding scheme into a VP scheme, or may convert h.264 into h.265.

In this way, the encoding process can be performed by the terminal or 1 or more servers. Therefore, the following description uses "server" or "terminal" as a main body for performing the processing, but a part or all of the processing performed by the server may be performed by the terminal, or a part or all of the processing performed by the terminal may be performed by the server. The same applies to the decoding process.

[3D, Multi-Angle ]

In recent years, there have been increasing cases where images or videos of different scenes captured by a plurality of terminals such as the camera ex113 and the smartphone ex115, which are substantially synchronized with each other, or images or videos of the same scene captured from different angles are combined and used. Images captured by the respective terminals are merged based on a relative positional relationship between the terminals acquired separately, or areas where feature points included in the images coincide, or the like.

The server may encode a still image automatically or at a time designated by a user based on scene analysis of a moving image and transmit the encoded still image to the receiving terminal, instead of encoding a two-dimensional moving image. When the relative positional relationship between the imaging terminals can be acquired, the server can generate a three-dimensional shape of the same scene based on images of the scene captured from different angles, in addition to the two-dimensional moving image. The server may encode three-dimensional data generated from a point cloud (point cloud) or the like separately, or may select or reconstruct videos captured by a plurality of terminals based on the result of recognizing or tracking a person or an object using the three-dimensional data, and generate a video to be transmitted to the receiving terminal.

In this way, the user can enjoy a scene by arbitrarily selecting each video corresponding to each imaging terminal, and can also enjoy the contents of a video cut from a three-dimensional data reconstructed using a plurality of images or videos from an arbitrary viewpoint. Further, similarly to the video, the audio may be collected from a plurality of different angles, and the server may multiplex and transmit the audio from a specific angle or space with the video in accordance with the video.

In recent years, contents such as Virtual Reality (VR) and Augmented Reality (AR) that correspond to the real world and the Virtual world have become widespread. In the case of VR images, the server creates viewpoint images for the right eye and the left eye, respectively, and may perform encoding allowing reference between the viewpoint images by Multi-View Coding (MVC) or the like, or may perform encoding as different streams without referring to each other. Upon decoding of different streams, they can be reproduced in synchronization with each other according to the viewpoint of a user to reproduce a virtual three-dimensional space.

In the case of an AR image, the server may superimpose virtual object information on the virtual space on camera information of the real space based on the three-dimensional position or the movement of the viewpoint of the user. The decoding device acquires or holds virtual object information and three-dimensional data, generates a two-dimensional image in accordance with the movement of the viewpoint of the user, and creates superimposed data by smoothly connecting the two-dimensional image and the three-dimensional data. Alternatively, the decoding device may transmit the movement of the viewpoint of the user to the server in addition to the request of the virtual object information, and the server may create the superimposition data in accordance with the received movement of the viewpoint from the three-dimensional data held in the server, encode the superimposition data, and distribute the superimposition data to the decoding device. The superimposition data has an α value indicating transmittance other than RGB, and the server sets the α value of a portion other than the target created from the three-dimensional data to 0 or the like, and encodes the superimposition data in a state where the portion is transmissive. Alternatively, the server may generate data in which the RGB values of the predetermined values are set as the background, such as the chroma key, and the portion other than the object is set as the background color.

Similarly, the decoding process of the distributed data may be performed by each terminal as a client, may be performed on the server side, or may be performed by sharing each terminal with each other. For example, a certain terminal may transmit a reception request to the server, receive a content corresponding to the request by another terminal, perform decoding processing, and transmit a decoded signal to a device having a display. By dispersing the processing and selecting appropriate contents regardless of the performance of the communicable terminal itself, data with good image quality can be reproduced. In another example, a large-size image data may be received by a TV or the like, and a partial area such as a tile into which a picture is divided may be decoded and displayed by a personal terminal of a viewer. This makes it possible to share the entire image and confirm the region in charge of the user or the region to be confirmed in more detail at hand.

In addition, in a situation where a plurality of wireless communications of a short distance, a medium distance, or a long distance can be used indoors and outdoors in the future, it is expected that content will be received seamlessly while switching appropriate data to the communication being connected, using a distribution system standard such as MPEG-DASH. Thus, the user can freely select a decoding device or a display device such as a display installed indoors or outdoors to switch in real time, not only by using his/her own terminal. Further, the decoding terminal and the displayed terminal can be switched and decoded based on the own position information and the like. This makes it possible to move the vehicle to a destination while displaying map information on a part of a wall surface or a floor surface of a building in which a display-enabled device is embedded. Further, the bit rate of the received data can be switched based on the ease of access to the encoded data on the network, such as caching the encoded data in a server that can be accessed from the receiving terminal in a short time, or copying the encoded data to an edge server of the content distribution service.

[ scalable encoding ]

The switching of contents will be described using scalable (scalable) streams that are compression-encoded by applying the moving picture encoding method shown in the above-described embodiment and each of the modifications shown in fig. 23. The server may have a plurality of streams having the same content and different qualities as a single stream, or may have a configuration in which the content is switched using the feature of temporally and spatially scalable streams obtained by layered coding as shown in the figure. That is, the decoding side can freely switch between the low-resolution content and the high-resolution content and decode the content by determining which layer to decode based on intrinsic factors such as performance and extrinsic factors such as the state of the communication band. For example, when a user wants to view a video that is viewed by the mobile smartphone ex115 later, after returning home, by an internet TV or other device, the device can decode the same stream to a different layer, and thus the load on the server side can be reduced.

Further, in addition to the structure in which pictures are coded for each layer as described above and the scalability in which an enhancement layer exists above a base layer is realized, an enhancement layer (enhancement layer) may include meta information such as statistical information based on an image, and a decoding side may generate content with high image quality by super-resolving pictures of the base layer based on the meta information. The super-resolution may be either an increase in the SN ratio or an increase in the resolution at the same resolution. The meta information includes information for specifying linear or nonlinear filter coefficients used in the super-resolution processing, or information for specifying parameter values in the filter processing, machine learning, or minimum 2-product operation used in the super-resolution processing, and the like.

Alternatively, a picture may be divided into tiles or the like according to the meaning of an object or the like in an image, and the decoding side may select a tile to be decoded to decode only a partial region. Further, by storing the attributes of the object (person, car, ball, etc.) and the position within the video (coordinate position in the same image, etc.) as meta information, the decoding side can specify the position of a desired object based on the meta information and determine a tile including the object. For example, as shown in fig. 24, meta information is saved using a data saving structure such as an SEI message in HEVC that is different from pixel data. The meta information indicates, for example, the position, size, color, or the like of the main target.

The meta information may be stored in units of a plurality of pictures, such as streams, sequences, and random access units. Thus, the decoding side can acquire the time when the specific person appears in the video, and the like, and can specify the picture in which the target exists and the position of the target in the picture by matching with the information in the picture unit.

[ optimization of Web Page ]

Fig. 25 is a diagram showing an example of a display screen of a web page in the computer ex111 and the like. Fig. 26 is a diagram showing an example of a display screen of a web page in the smartphone ex115 or the like. As shown in fig. 25 and 26, in some cases, a web page includes a plurality of link images as links to image content, and the visibility is different depending on the viewing device. When a plurality of link images are visible on the screen, before the user explicitly selects a link image, or before the link image is close to the center of the screen or the entire link image is entered into the screen, a display device (decoding device) displays a still image or an I picture included in each content as a link image, displays a video such as gif moving picture using a plurality of still images or I pictures, or receives only a base layer and decodes and displays the video.

In the case where the link image is selected by the user, the display apparatus decodes the base layer with the highest priority. In addition, if information indicating content that is scalable is present in HTML constituting a web page, the display apparatus may decode to the enhancement layer. In addition, when there is a shortage of communication bands or before selection in order to ensure real-time performance, the display device can reduce a delay between the decoding time and the display time of the leading picture (delay from the start of decoding of the content to the start of display) by decoding and displaying only the picture to be referred to ahead (I picture, P picture, B picture to be referred to ahead only). The display device may also perform rough decoding by forcibly ignoring the reference relationship of pictures, using all B pictures and P pictures as forward references, and perform normal decoding by increasing the number of received pictures with the passage of time.

[ automatic traveling ]

In addition, when transmitting and receiving still images or video data such as two-dimensional or three-dimensional map information for automatic travel or travel assistance of a vehicle, the receiving terminal may receive weather or construction information as meta information in addition to image data belonging to 1 or more layers, and decode the information in association with the received information. The meta information may belong to a layer or may be multiplexed with only the image data.

In this case, since the vehicle, the drone, the airplane, or the like including the receiving terminal is moving, the receiving terminal can switch the base stations ex106 to ex110 to perform seamless reception and decoding by transmitting the location information of the receiving terminal when receiving the request. The receiving terminal can dynamically switch to how much meta information is received or how much map information is updated, depending on the selection of the user, the situation of the user, or the state of the communication band.

As described above, in the content providing system ex100, the client can receive, decode, and reproduce encoded information transmitted by the user in real time.

[ distribution of personal content ]

In addition, the content supply system ex100 can distribute not only high-quality and long-time content provided by a video distribution provider but also low-quality and short-time content provided by an individual by unicast or multicast. Further, it is conceivable that such personal content will increase in the future. In order to make the personal content a better content, the server may perform an encoding process after performing an editing process. This can be achieved by the following structure, for example.

When shooting is performed in real time or accumulated, the server performs recognition processing such as shooting error, scene search, meaning analysis, and object detection based on the original image or encoded data. The server manually or automatically performs editing such as correction of focus deviation or camera shake, deletion of a scene with lower brightness than other pictures or a scene with no focus, enhancement of an edge of a target, and change of color tone, based on the recognition result. And the server encodes the edited data based on the editing result. It is also known that the audience rate decreases if the shooting time is too long, and the server may automatically clip, based on the image processing result, not only scenes with low importance as described above but also scenes with little motion, so as to have contents within a specific time range, according to the shooting time. Alternatively, the server may generate a summary based on the result of the meaning analysis of the scene and encode the summary.

In addition, in some cases, contents infringing copyright, copyright of a writer, portrait right, and the like are written in the original state of personal contents, and there is a case where it is inconvenient for a person that the shared range exceeds a desired range. Therefore, for example, the server may encode the image by forcibly changing the face of a person around the screen or the home or the like to an out-of-focus image. The server may recognize whether or not a face of a person different from a person registered in advance is captured in the image to be encoded, and may perform processing such as mosaic processing on the face portion when the face is captured. Alternatively, as the pre-processing or post-processing of the encoding, the user may specify a person or a background region to be processed from the viewpoint of copyright or the like, and the server may perform processing such as replacing the specified region with another video or blurring the focus. If the face is a person, the image of the face portion can be replaced while the person is tracked in the moving image.

Further, since viewing of personal content with a small data amount requires high real-time performance, the decoding device receives the base layer first with the highest priority, decodes the received base layer, and reproduces the decoded base layer, depending on the bandwidth. The decoding device may receive the enhancement layer during this period, and may include the enhancement layer in the case of being played back more than 2 times, such as when playback is looped, to play back the high-quality video. In this way, if the stream is scalable-coded, it is possible to provide an experience in which the stream becomes smooth and the image becomes better although the moving image is relatively coarse at the time of non-selection or at the beginning of viewing. In addition to scalable encoding, the same experience can be provided even when the 1 st stream to be reproduced and the 2 nd stream to be encoded with reference to the 1 st video are 1 stream.

[ other use examples ]

These encoding and decoding processes are usually performed in LSIex500 provided in each terminal. LSIex500 may be a single chip or a structure made up of multiple chips. Alternatively, software for encoding or decoding a moving picture may be loaded into a recording medium (such as a CD-ROM, a flexible disk, or a hard disk) that can be read by the computer ex111 or the like, and encoding and decoding processes may be performed using the software. Further, when the smartphone ex115 is equipped with a camera, the moving image data acquired by the camera may be transmitted. The moving image data at this time is data subjected to encoding processing by LSIex500 of the smartphone ex 115.

Alternatively, LSIex500 may be a structure that downloads application software and activates it. In this case, the terminal first determines whether the terminal corresponds to the encoding method of the content or has the performance capability of the specific service. When the terminal does not support the encoding system of the content or does not have the capability of executing a specific service, the terminal downloads the codec or application software and then acquires and reproduces the content.

In addition, not only the content providing system ex100 via the internet ex101, but also at least one of the moving image encoding device (image encoding device) and the moving image decoding device (image decoding device) according to the above-described embodiments and modifications may be incorporated into the digital broadcasting system. Since multiplexed data obtained by multiplexing video and audio is transmitted and received by using broadcast radio waves such as satellites, there is a difference in that the content providing system ex100 is suitable for multicast in a configuration that facilitates unicast, but the same application can be made to encoding processing and decoding processing.

[ hardware configuration ]

Fig. 27 is a diagram showing the smartphone ex 115. Fig. 28 is a diagram showing a configuration example of the smartphone ex 115. The smartphone ex115 includes an antenna ex450 for transmitting and receiving radio waves to and from the base station ex110, a camera unit ex465 capable of capturing video and still images, and a display unit ex458 for displaying data obtained by decoding the video captured by the camera unit ex465, the video received by the antenna ex450, and the like. The smartphone ex115 further includes an operation unit ex466 such as a touch panel, an audio output unit ex457 such as a speaker for outputting audio or sound, an audio input unit ex456 such as a microphone for inputting audio, a memory unit ex467 capable of storing encoded data or decoded data of captured video or still images, recorded audio, received video or still images, mail, and the like, or SIMex468 for identifying a user and authenticating access to various data on behalf of a network, or an insertion unit ex464 as an interface with the SIMex 468. In addition, an external memory may be used instead of the memory unit ex 467.

The main control unit ex460 that comprehensively controls the display unit ex458, the operation unit ex466, and the like is connected to the power supply circuit unit ex461, the operation input control unit ex462, the video signal processing unit ex455, the camera interface unit ex463, the display control unit ex459, the modulation/demodulation unit ex452, the multiplexing/separation unit ex453, the audio signal processing unit ex454, the slot unit ex464, and the memory unit ex467 via the bus ex 470.

The power supply circuit unit ex461 activates the smartphone ex115 to be operable by supplying power from the battery pack to each unit if the power key is turned on by the user's operation.

The smartphone ex115 performs processing such as call and data communication under the control of a main control unit ex460 having a CPU, ROM, RAM, and the like. During a call, the audio signal processing unit ex454 converts the audio signal collected by the audio input unit ex456 into a digital audio signal, performs spectrum spreading processing on the digital audio signal by the modulation/demodulation unit ex452, performs digital-to-analog conversion processing and frequency conversion processing by the transmission/reception unit ex451, and transmits the digital audio signal via the antenna ex 450. The received data is amplified, subjected to frequency conversion processing and analog-digital conversion processing, subjected to spectrum inverse diffusion processing by the modulation/demodulation unit ex452, converted into an analog audio signal by the audio signal processing unit ex454, and then output from the audio output unit ex 457. In data communication, text, still image, or video data is transmitted to the main control unit ex460 via the operation input control unit ex462 by operation of the operation unit ex466 of the main body unit, and the transmission/reception processing is performed in the same manner. In the data communication mode, when transmitting video, still images, or video and audio, the video signal processing unit ex455 performs compression coding on the video signal stored in the memory unit ex467 or the video signal input from the camera unit ex465 by the moving image coding method described in the above-described embodiment and the modifications, and transmits the coded video data to the multiplexing/demultiplexing unit ex 453. The audio signal processing unit ex454 encodes an audio signal collected by the audio input unit ex456 during shooting of a video, a still image, or the like by the camera unit ex465, and sends the encoded audio data to the multiplexing/demultiplexing unit ex 453. The multiplexing/demultiplexing unit ex453 multiplexes the coded video data and the coded audio data in a predetermined manner, and the modulation and conversion processing is performed by the modulation/demodulation unit (modulation/demodulation circuit unit) ex452 and the transmission/reception unit ex451, and the data is transmitted via the antenna ex 450.

When receiving a video attached to an e-mail or a chat tool, or a video linked to a web page or the like, the multiplexing/demultiplexing unit ex453 demultiplexes the multiplexed data into a video data bit stream and a voice data bit stream by demultiplexing the multiplexed data, and supplies the encoded video data to the video signal processing unit ex455 and the encoded voice data to the voice signal processing unit ex454 via the synchronous bus ex470, respectively, in order to decode the multiplexed data received via the antenna ex 450. The video signal processing unit ex455 decodes the video signal by a moving image decoding method corresponding to the moving image coding method described in the above-described embodiment and each modification, and displays the video or still image included in the linked moving image file from the display unit ex458 via the display control unit ex 459. The audio signal processing unit ex454 decodes the audio signal, and outputs the audio signal from the audio output unit ex 457. In addition, since real-time streaming is becoming popular, it is possible that playback of sound is socially inappropriate depending on the situation of the user. Therefore, as the initial value, a configuration is preferable in which only video data is reproduced without reproducing an audio signal. The audio may be reproduced in synchronization only when the user performs an operation such as clicking on the video data.

Note that, although the smart phone ex115 is described as an example, 3 types of installation forms of a transmitting terminal having only an encoder and a receiving terminal having only a decoder, in addition to a transmitting/receiving terminal having both an encoder and a decoder, are conceivable as terminals. Further, in the digital broadcasting system, although the explanation has been given assuming that multiplexed data such as audio data is received and transmitted while multiplexed data in which audio data is multiplexed with video data, the multiplexed data may be multiplexed with character data or the like associated with video in addition to audio data, or may be received or transmitted not as multiplexed data but as video data itself.

Further, the main control unit ex460 including the CPU controls the encoding and decoding processes, but the terminal often includes a GPU. Therefore, a configuration may be adopted in which a large area is processed at once by utilizing the performance of the GPU by using a memory shared by the CPU and the GPU or a memory for managing addresses so as to be commonly usable. This shortens the encoding time, ensures real-time performance, and realizes low delay. In particular, it is more effective if the processes of motion estimation, deblocking filtering, sao (sample Adaptive offset), and transformation/quantization are not performed by the CPU but are performed together in units of pictures or the like by the GPU.

Industrial applicability

The present invention can be used in, for example, television receivers, digital video recorders, car navigation systems, mobile phones, digital cameras, digital video cameras, and the like. .

Description of the reference symbols

100 encoder

102 division part

104 subtraction part

106 transformation part

108 quantization part

110 entropy coding part

112. 204 inverse quantization unit

114. 206 inverse transformation part

116. 208 addition unit

118. 210 block memory

120. 212 loop filter part

122. 214 frame memory

124. 216 intra prediction unit

126. 218 inter prediction unit

128. 220 prediction control unit

200 decoding device

202 entropy decoding unit

Claims

1. An encoding device for encoding a block to be encoded of a picture,

the circuit includes a circuit and a memory, and the circuit performs the following processing using the memory:

generating a 1 st transform coefficient by performing a 1 st transform on a residual signal of the block to be encoded using a 1 st transform base,

when the 1 st transform base matches a predetermined transform base, performing a 2 nd transform on the 1 st transform coefficient using a 2 nd transform base to generate a 2 nd transform coefficient, quantizing the 2 nd transform coefficient,

when the 1 st transform base is different from the predetermined transform base, the 1 st transform coefficient is quantized without performing the 2 nd transform.

2. The encoding apparatus according to claim 1,

whether the 1 st transformation base matches the predetermined transformation base is determined based on identification information indicating whether an adaptive base selection mode for adaptively selecting the 1 st transformation base from among a plurality of 1 st transformation base candidates is valid.

3. The encoding apparatus according to claim 1 or 2,

the above-specified transform base is a base of DCT-II which is a transform type of discrete cosine transform,

the DCT-II uses a basis function Ti (j) represented by the following formula,

wherein,

i，j＝0，1，…，N-1，

n denotes the number of input pixels of the transform process.

4. An encoding method for encoding a block to be encoded of a picture,